SKU: 9262877285

Kidde KF21R Sentry Mains Powered Optical Smoke Alarm with Sealed-In Rechargeable Lithium Battery Back-Up c/w Quick Fit Base

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Description

Kidde KF21R Sentry Mains Powered Optical Smoke Alarm with Sealed-In Rechargeable Lithium Battery Back-Up c/w Quick Fit BaseKidde KF21R Sentry Mains Powered Optical Smoke Alarm with Rechargeable Lithium Battery Back Up The Kidde KF21R Sentry Optical Smoke Alarm is a high performance mains powered smoke detector designed to provide dependable fire detection throughout residential properties. Featuring an advanced optical sensor, the KF21R is ideal for detecting slow, smouldering fires commonly caused by upholstered furniture, electrical faults and cigarettes. Equipped with

Kidde KF21R Sentry Mains Powered Optical Smoke Alarm with Rechargeable Lithium Battery Back-Up

The Kidde KF21R Sentry Optical Smoke Alarm is a high-performance mains-powered smoke detector designed to provide dependable fire detection throughout residential properties. Featuring an advanced optical sensor, the KF21R is ideal for detecting slow, smouldering fires commonly caused by upholstered furniture, electrical faults and cigarettes.

Equipped with a sealed rechargeable lithium battery back-up, this alarm continues to operate during mains power failures without the need for battery replacement. The KF21R can also be interconnected with up to 23 compatible Kidde FIREX smoke, heat and carbon monoxide alarms, ensuring all alarms sound simultaneously when danger is detected.

Designed for straightforward installation, the alarm features Kidde’s Quick-Fit Slide-On Base for fast, tool-free fitting. The integrated cable management system helps maintain tidy wiring, while the 150mm flared base provides a neat finish during retrofit projects.

Key Features

  • Mains-powered optical smoke alarm with sealed rechargeable lithium battery back-up
  • Interconnects with up to 23 compatible Kidde FIREX alarms
  • Optical sensor technology for detecting slow, smouldering fires
  • Quick-Fit Slide-On Base for fast, tool-free installation
  • 150mm flared base plate for neat retrofitting
  • Integrated cable management for secure and tidy wiring
  • Alarm memory identifies the activated unit within the network
  • Combined Test/Hush button for easy testing and temporary silencing
  • Automatic reset after alarm activation
  • Tamper-resistant locking mechanism for added security
  • Suitable for lofts, hallways, bedrooms and living areas
  • Fully compatible with Kidde FIREX smoke, heat and CO alarms
  • 10-year manufacturer warranty

Ideal Applications

The Kidde KF21R optical smoke alarm is recommended for installation in:

  • Hallways and circulation routes
  • Bedrooms
  • Living rooms
  • Attics and loft spaces
  • Residential Grade D1 fire alarm systems

Optical smoke alarms are particularly effective at detecting slow-burning fires and are ideal for escape routes and living spaces.

Technical Specifications

  • Model: KF21R
  • Power Supply: 230V mains with sealed rechargeable lithium battery back-up
  • Sensor Type: Optical with dust compensation and bug screen
  • Alarm Volume: Minimum 85dB at 3 metres
  • Alarm Frequency: 3.2 kHz typical
  • Interconnectivity: Up to 23 compatible alarms
  • Alarm Grade: D1
  • Approvals: BSI certified to BS EN14604:2005
  • Dimensions: 150mm x 150mm x 53mm
  • Weight: 260g including battery
  • Operating Temperature: -10°C to +40°C
  • Humidity Range: Up to 93% RH non-condensing
  • Warranty: 10 Years

Compliance & Installation

The Kidde KF21R complies with UK Building Regulations and BS 5839 Part 6 standards for Grade D domestic fire alarm systems. Installation should be completed by a qualified electrician. For kitchen installations, a dedicated Kidde FIREX heat alarm is recommended instead of a smoke alarm.

Downloads

Data Sheet:
Download Data Sheet

Instruction Manual:
Download Instruction Manual

Shipping Notes
  • Free Standard Shipping on $100+ Orders to the USA.
  • Except Preorder products are shipped in 48 hours.
  • Delivery to the USA:
  1. Standard Shipping : 3-10 business days
  • If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
  • We offer a 30-day return/exchange service after receiving.
  • Final sale items are not eligible for returns or exchanges.
  • To process your return/exchange, please contact us at [email protected]
  • Please click here for more details>>> Return & Exchange Policy
SKU: 9262877285

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4.2 ★★★★★
Based on 10 reviews
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Verified Purchase
DeeJayBee
Pawtucket, US
★★★★★ 3
Made my blush look orangey
Size: 1.8 Fl Oz (Pack of 1), Color: Original
I absolutely loved the feel and finish of this tinted sunscreen, but with or without my foundation on top of it, my Benefit Dandelion blush went from pink to a shade of orange. I have fair skin, blue eyes and strawberry blonde hair, which at this time of year is more strawberry than blonde. The orangey shade is definitely not my color. I was sad that this didn't work out, because the Colorscience made my skin look radiant really, until an hour or so after blush was applied. I so wanted a replacement for the Australian Gold Mineral sunscreen in original tint, because even though that tint looks great color-wise, it also makes my skin look dry and therefore accentuates my wrinkles, even when I mix it with Olay microsculpting cream moisturizer before I apply it. The Colorscience didn't accentuate the wrinkles. I feel certain this color issue is either a conflict with my Olay moisturizer, my own chemistry or the Benefit blush; maybe a combination of the three. If you have oily skin this sunscreen is moisturizing so it might not work for you. Otherwise, you may want to give this a try. Hate that I had to return it. No matter what, I've had a run-in with skin cancer, so I won't go without spf. I just have to keep looking ancient and dry with AG until I find one that works better for my coloring, skin type, and that plays well with my moisturizer and blush. I'm 62 yrs young, normal to dry combo skin. Hope this helps!
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on March 20, 2022
L
Verified Purchase
ladybossplanner
San Leandro, US
★★★★★ 5
Brown skin friendly! No white cast! 🥳 Bye dark spots!
Size: 2.6 Fl Oz (Pack of 1), Size: 2.6 Fl Oz (Pack of 1)
Brown skin friendly! No white cast! 🥳 Colorescience comes through again! This is a fantastic sunscreen. It’s SPF 50 and it protects against blue light. So if you’re trying to get rid of hyperpigmentation, this will help you on your journey. I usually use tinted sunscreen for that reason but luckily, we have a non-tinted option with this! I use this primarily on my body because it doesn’t get stain clothing. But sometimes I use it on my face too, on its own or under a tinted formula. I like the light coverage for my face to even out my skin tone. The texture is light and thin; reminds me of Tatcha silk screen but without the slight tint. This goes on white but somehow disappears into my skin. Also the price point is a better value, here. Even better when it’s on sale! I love Tatcha and use it regularly but I am happy to have this in my stash now. I had to get the big bottle when it was on sale. The formula is very elegant and leaves a natural finish. It spread and blends like a dream! It is so quick! You will NOT have to rub this in for 30 minutes to get it to blend. This physical sunscreen is a daily essential for me. It doesn’t burn my eyes or irritate my oily skin. It’s water resistant for 40 min, so it’s good for the summer heat. But where are all the photos? Cause sometimes we need proof, right? Well, here is my contribution. I’m wearing this on my body (neck, chest, arms, legs, hands and feet). * I reached out to Colorescience to ask about the effectiveness against UVA (aging) rays for this product. Other countries will usually mark this on a PA scale, the strongest protection being PA++++. But in the US, sunscreen isn’t required to specify how much; they are required to make sure it has at least the FDA “minimum” protection against UVA, and UVB (burning) rays and they have to label it “Broad Spectrum.” SPF is the protection level against UVB only. Colorescience has started to label some of their products with PA++++. Since this wasn’t labeled like that, I asked. They told me they recently completed testing and No-Show has earned the PA++++ rating. So they are in the process of updating the packaging. Colorescience knows what we want, even though the FDA is asleep at the wheel.
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Reviewed in the United States on June 2, 2025
A
Verified Purchase
azra
Draper, US
★★★★★ 5
It Works REALLY well
Size: 1.7 Fl Oz (Pack of 1)
I have Lupus with Eczema and Psoriasis, and my skin is really sensitive. I was trying to find a sunscreen that wouldn't break out my skin when I was out and at home. I was looking on YouTube and came across a channel, DrDillyOfficial. She herself has eczema, so when she recommended the brand, I took a chance to buy this, and it was one of the best choices I made for my skin. Its cast free, very light weight and it has a nice glow effect so it doesnt make you shiny but the glow effect I love. When you're outside, you forget you even have it on its that good. I would highly recommend this it has been a life saver when going outside and worrying about sun protection
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Reviewed in the United States on March 31, 2026
K
Verified Purchase
Kiki
New York, US
★★★★★ 5
Perfect daily face sunscreen
Size: 1.7 Fl Oz (Pack of 1)
Best daily sunscreen I have tried. Not greasy & leaves no white cast. Did not break out my face. It seems to make my skin look smoother & healthier while protecting it from daily sun damage. The consistency is not thick or too watery. It is thin enough to go on smooth and quickly. Just shake the bottle and lightly squeeze the tip onto your finger or face and smooth on evenly. Can be used under makeup as a base.
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Reviewed in the United States on January 4, 2026
A
Verified Purchase
Amazon Customer
Lake Worth, US
★★★★★ 5
Stays in place no white cast. THE BEST!
Size: 1.7 Fl Oz (Pack of 1)
BEST facial sunscreen I have ever used. I also use Color Science tinted sunscreen when I’m not wearing any “makeup” . I was looking for a sunscreen to use under my regular makeup. I’ve tried several products that were highly recommended . This sunscreen actually makes my high-end makeup look smoother, softer and even looks to blur the wrinkles more than just the makeup. My makeup stays put it doesn’t pill, shred or melt off. I also wear it without makeup when exercising outdoors, so of course I’m going to sweat. It doesn’t burn my eyes if I sweat and actually stays in place. I also put it on my neck and Décolletage and it does not melt off. I know it’s pricey, but it’s worth it. I highly recommend this product. Check out the other Color Science tinted sunscreen It’s amazing too.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on July 26, 2025

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