12/24 volt anti-zap surge protector. Simply clip the booster clamps across the vehicles battery, and when the green led illuminates the system is then protected from spikes and surges while the vehicle is being worked on. features and benefits: simply clip the booster clamps accross the battery, and when the green led illuminates the system is then protected from spikes and surges while the vehicle is being worked on body shops and muffler shops can use the service minder when carrying out all forms of electric welding, including tig, argon arc and mig, on a vehicle with the battery connected!! the service minder not only protects the on-board electronics but dispenses with the need to disconnect the battery resulting in lost stereo and other electronic memories fully insulated booster clamps with 2-function antizap protection red indicates no antizap protection, while green indicates correct anitizap protection