Square Pair Packed 12V 12 Volt 3 Digit Blue Digital Volt Meter Pair Packed. Pack of 2. Unit requires a mounting hole of exactly 2 1/16" x 1 5/8". Overall measurement is 2 3/4" x 2" x 1" (depth) Square Blue 3 Digit Display. Flush or Surface Mount. Auto Sense Turn On. Silver Finish, Weatherproof ABS Plastic to Resist the Elements. Faux Allen Key Design. Compatible with all 12-volt systems, Simple 2 Wire Installation. Lightweight and compact design allows installation in tight fitting spaces.