See: T-Work’s

T-Work’s have introduced two aluminium glow plug igniters, one being featured with a voltage meter in the cap. Both come with an aluminium body with a grey anodised finish and work with any 1.2V cell (not included) that can be easily changed if the cell is damaged or needs to be recharged. The glow plug igniter with a voltage meter will let you know if the glow plug in the engine is damaged (red = broken, green = ok).