SKU: 71848446569

Kidde Sentry 4x KF21R Optical Smoke & 1x KF31R Heat Alarm Kit Mains Powered with Sealed-In Rechargeable Battery Back-Up c/w Quick Fit Base

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Description

Kidde Sentry 4x KF21R Optical Smoke & 1x KF31R Heat Alarm Kit Mains Powered with Sealed-In Rechargeable Battery Back-Up c/w Quick Fit BaseKidde Sentry 4x KF21R Optical Smoke & KF31R Heat Alarm Kit with Rechargeable Lithium Battery Back Up The Kidde Sentry Alarm Kit includes four KF21R Optical Smoke Alarms and one KF31R Heat Alarm, providing a complete fire detection solution for larger homes and multi storey residential properties. Designed for mains powered installation, each alarm features a sealed rechargeable lithium battery back up and can be interconnected with up to 23 compatible

Kidde Sentry 4x KF21R Optical Smoke & KF31R Heat Alarm Kit with Rechargeable Lithium Battery Back-Up

The Kidde Sentry Alarm Kit includes four KF21R Optical Smoke Alarms and one KF31R Heat Alarm, providing a complete fire detection solution for larger homes and multi-storey residential properties. Designed for mains-powered installation, each alarm features a sealed rechargeable lithium battery back-up and can be interconnected with up to 23 compatible Kidde FIREX alarms.

When one alarm detects danger, all connected alarms sound simultaneously, helping to provide an early warning throughout the property. This makes the system ideal for improving fire safety across multiple rooms, hallways, landings and escape routes.

Each alarm is supplied with Kidde’s Quick-Fit Slide-On Base for fast installation and features integrated cable management to keep wiring secure and organised. The 150mm flared base plate also provides a neat retrofit finish when replacing older alarms.

Kit Contents

  • 4 x Kidde KF21R Optical Smoke Alarms
  • 1 x Kidde KF31R Heat Alarm

KF21R Optical Smoke Alarm Features

The Kidde KF21R optical smoke alarm is designed to detect slow, smouldering fires caused by electrical faults, furniture or cigarettes. Ideal for circulation routes and living areas, the optical sensor provides dependable early warning protection.

  • Mains-powered optical smoke alarm with sealed rechargeable lithium battery back-up
  • Optical sensor with dust compensation and bug screen
  • Interconnects with up to 23 Kidde FIREX alarms
  • Alarm memory identifies the activated alarm
  • Combined Test/Hush button
  • Auto reset after activation
  • Tamper-resistant locking mechanism
  • Suitable for hallways, bedrooms, lofts and living rooms
  • BSI certified to BS EN14604:2005
  • 10-year warranty

KF31R Heat Alarm Features

The Kidde KF31R heat alarm is ideal for kitchens, garages and loft spaces where smoke alarms may be unsuitable due to cooking fumes, steam or airborne dust. The thermistor heat sensor delivers reliable heat detection while helping reduce nuisance alarms.

  • Mains-powered heat alarm with sealed rechargeable lithium battery back-up
  • Thermistor heat sensor for dependable heat detection
  • Interconnects with up to 23 Kidde FIREX alarms
  • Alarm memory identifies the activated alarm
  • Combined Test/Hush button
  • Auto reset after activation
  • Tamper-resistant locking mechanism
  • Ideal for kitchens, garages and loft spaces
  • BSI certified to BS 5446 Part 2:2003
  • 10-year warranty including battery

Key Benefits

  • Complete smoke and heat alarm solution for larger homes
  • Sealed rechargeable lithium battery back-up for maintenance-free operation
  • Interlinked alarms provide whole-home warning when danger is detected
  • Quick-Fit bases for fast and efficient installation
  • Integrated cable management for neat wiring
  • Suitable for compliance with UK Building Regulations
  • Grade D1 domestic fire alarm system solution
  • Fully compatible with Kidde FIREX smoke, heat and CO alarms

Technical Specifications

KF21R Optical Smoke Alarm

  • Model: KF21R
  • Power Supply: 230V mains with sealed rechargeable lithium battery back-up
  • Sensor Type: Optical
  • Alarm Volume: 85dB minimum at 3 metres
  • Dimensions: 150mm x 150mm x 53mm
  • Weight: 260g
  • Operating Temperature: -10°C to +40°C
  • Warranty: 10 Years

KF31R Heat Alarm

  • Model: KF31R
  • Power Supply: 230V mains with sealed rechargeable lithium battery back-up
  • Sensor Type: Thermistor heat sensor
  • Alarm Volume: 85dB minimum at 3 metres
  • Dimensions: 150mm x 66mm
  • Weight: 245g
  • Operating Temperature: -10°C to +40°C
  • Warranty: 10 Years including battery

Please Note: Alarms are supplied individually within the kit. Installation should be completed by a qualified electrician.

Downloads

KF21R Data Sheet:
Download KF21R Data Sheet

KF31R Data Sheet:
Download KF31R Data Sheet

KF21R Instruction Manual:
Download KF21R Instruction Manual

KF31R Instruction Manual:
Download KF31R 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: 71848446569

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4.3 ★★★★★
Based on 11 reviews
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Ray Ray
Dallas, US
★★★★★ 5
Excellent choice
I will skeptical when buying these because I have a pitbull bulldog that likes to chew holes in every toy. This is her favorite she choose on the ball, but she doesn’t actually ruin it because she can’t. It holds up one of the squeakers broke, but that’s expected I guess my wife actually ordered more. I’m not sure if it was from the same seller or not but those ones they don’t favor as much for some reason I seen the same different colors. My dog even sleeps with it sometimes. The picture shows for sleeping with it. I’m definitely happy. I got these. They are tough. I like the fact that they have those little recessed holes so they can grab a hold of it and not get it all slimy like the other balls we have.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on April 23, 2026
T
Verified Purchase
Tyrek
Boise, US
★★★★★ 5
Durable and a must have for aggressive chewers
Color: Blue+Red
These are without a doubt the best toys that I have ever purchased for my dog. He's an aggressive chewer and quickly destroys almost every toy I buy. This one hasn't been destroyed yet and the squeaker is still working at about 5 months.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on June 11, 2026
K
Verified Purchase
Kassy
Waukegan, US
★★★★★ 5
GSD Winner
Color: Blue+Red
10/10 recommend for big dogs with a tough chew. Our GSD absolutely loves these squeaky balls. They have perfect texture for his teeth and for our grip. They are the size of a baseball and are so durable and fun. Yes the squeaky is LOUD but he loves them so much that it's cute
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on May 12, 2026
P
Verified Purchase
phan_graph
Cuba, US
★★★★★ 4
Great buy
Color: Blue+Red
My dogs kill every toy. They arrived very agressive chewers. These have lasted way longer than most balls have. Great value
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on April 24, 2026
M
Verified Purchase
megs2168
West Palm Beach, US
★★★★★ 5
If your dog loves tennis balls, you NEED these
Color: Azure+Orange, Color: Azure+Orange
Raising any puppy is tough. Raising a German Shepherd puppy has often left me questioning my life choices. So I was ecstatic the day that my 60-lb puppy decided that he loves tennis balls and occupied himself for 2 hours without needing constant intervention. Naturally, my immediate response was to make sure we had a constant supply of large tennis balls for dogs available. Now my puppy loves mischief, but he’s not an aggressive chewer. And I was irritated to discover that every brand and size of tennis ball broke within an hour max of play. By simply playing fetch and batting the ball around with his paws, every single tennis ball split into 2 halves. We needed something better! These squeaky balls are exactly that! They come in a 2-pack. I gave my pup the 1st one a week ago and it’s still going strong! We play fetch in the backyard, he brings it into the doggy pool with him, it rolls around in the dirt and can be rinsed off easily. It’s by far his favorite toy, and he takes it everywhere with him. Finally a squeaky ball that can keep up with my dog! These are the perfect size, texture, bounce, squeak, everything. These are the ONLY squeaky balls I will buy from now on. Five stars for sure!
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on March 12, 2026

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