This Timeguard Electronic 4 Hour Boost Timer and Fused Spur - FBT4N is part of the BoostMaster range, featuring fused spur countdown switches that provide timed output protected by a BS1362 fuse switch. It offers automatic timed countdown selections to a fail-safe OFF with simple push-button programming and clear LED output status. This unit can easily replace existing single-gang connection units or fixed appliance outlets. Up to 5 ON times can be selected: 1/4hr, 1/2hr, 1, 2, and 4 hours. It's ideal for immersion and room heaters, automatically switching off at the end of the set time period. The device fits a standard flush or surface-mount BS wall box (minimum 25mm).