Use this gauge / volt meter when you do not want to monitor amps. Fits: FarmalI / IH tractors / Vintage trucks / equipment with 2"/ 52mm mounting hole. Can also be used as a universal gauge / meter for other applications. Mount it in and under dash mount bracket applications also. Gauge has a range of 8 - 18 volts. This is a nice volt gauge! Looks nice and it's different for a change! This gauge is not to be used in place of Amp Gauge! It will not carry amps or current! It will Fry! It is a Volt Meter! This Volt gauge / meter wiring connects: + to 12v Terminal On Ignition Switch or Other 12v Source! - Connects To Engine Ground! Wiring should have a grommet installed when wiring is going thru sheet metal holes! Not to be used as Amp meter replacement! Farmall / IH tractors / Diesel trucks IH trucks include: Scouts, Travleall, IH Harvester pickups, Ford 6.0 and 7.3 Diesel Conversions