Size:2 inch gauge or 52 mm diameter Power:Professional 12V,IGN MAX 0.3A Reads: 15v Warning (Red Light):Voltage lower 11.5V Black Shell Universal fit for: most of cars or motors How to installation: 1.Gauge May Be Mounted In 2"/52mm Dia holes Or In Auto Gauge Custom Mounted Panels .Secure Gauge With Mounting Clamps Supplied. 2.Drill 3/8" Dia .Holes And Install Rubber Grommets Where Pressure Or Vacuum Line Passes Through Sheet Mental Such As Firewall. 3.Attach Nylon Pressure Line To Fitting On Back Of Gauge Using Adaptor ,Ferrule ,And Compression nut .Route Line Through Grommets To Engine Compartment .Connect Line To Pressure port On Engine By Using 1/8" Adaptor Ferrule And Compression Nut For Turbo And Prossure Gauge Or 1/8" Adaptor And Fitting For Vacuum Gauge. 4.Start Engine And Thoroughly Check Installation For Leaks. Twist In Light Socket Assembly And Connect One Wire(Yellow) To Dash Lighting Circut Or Other 12V Power Source And The Other Wire(Black) To A Good Ground. Package : 1 X Digital LED Volt Gauge