Excellent for marine or automotive use. Interrupts electrical circuit between battery and starter. An effective deterrent against theft, fire and damage caused by short circuits. Rate 100A continuous, 1000A surge at 12V and 50A continuous, 500A surge at 24V. 2-1/4 in. diam. x 2-1/2 in. deep (1 -1/4 in. deep behind panel). Two 3/16 in. diam. mounting holes. Extra key and waterproof cover included. 1/clamshell.