Digital Tachometer, Marine, 2 InchProduct Details:A Tachometer Measures Your Boat Engine’s RPMsTachometer Picture Taken With Protective, Removable Cover Over FaceWorking Voltage 12 Volt DCCylinder Selection Switch on Back Of Tach for 4, 6 or 8 Cylinder EngineDisplay Type: Digital, Blue LED, 4 DigitWhite Plastic Case with Light Gray Trim RingMounting Hole Required: 2.063 InchTachometer Depth: 2.15 InchThree 22 Inch Long Wire Connection:Red: To Ignition Switch 12 Volt PositiveBlack: To Battery NegativeGreen: On Standard Coil Ignition Attach Wire To Negative Side Of CoilBocatechBT-TACH