FIREANGEL FireAngel Toast Proof Smoke Detector SB1-R. 1 Year Replaceable Battery. The FireAngel SB1-R Smoke Alarm has been designed to make protecting your caravan & Motorhome simple, with easy install and testing and rigorous testing by independent parties, such as BSI Kitemark, to ensure quality and longevity.3 Year Warranty. The optical smoke sensing chamber works by seeing smoke as it enters the alarm - making it perfect for slow burning fires where there is thick white smoke. Sold in singles or Outer Boxes x 5.