Housed in tough composite cases, these units are designed to prevent damaging voltage spikes and surges reaching delicate vehicle electronics. Clips across the battery terminals and permits processes such as welding and plasma cutting to be carried out without the danger of damaging the vehicles on board electronics. Fitting recommended before any routine workshop maintenance. Shows green light when unit is operating correctly (Prosaf/12 only) and red light for fault. Both units fitted with heavy-duty, fully insulated battery clips.