The Pilot Mini Gas Alarm has a single gas alarm. The unit is designed to detect butane, propane gases and will detect fuel vapours. It has one gas detection sensor on a 3.5metre length of 3-core cable. The unit draws 98 milliamps at standby rising to 100 milliamps in the event of an alarm. Dimensions: 35mm x 53mm x 100mm The Dual Gas Alarm has two sensors on 3.5metres of 3-core cable. The unit draws 178 milliamps at standby rising to 210 milliamps in the event of an alarm. Dimensions: 35 x 65 x 120mm