The Spectrex SharpEye 40/40C-L4B is capable of detection Hydrocarbon fuel and gas fires and responds in under 5 seconds. The units work with an integrated UV and optical IR sensor in the 4.5 micron area. This allows for a higher false alarm immunity and greater detection capabilities then other regular UV/IR models on the market. With this proven record of false alarm immunity these Spectrex NexGen 40/40-C-L4B units keep a SharpEye on your Safety!