INSIZE Electronic Depth Gage w/ Round Depth Bar Features include... 0-8" / 200mm Measuring Range 0.0005" / 0.01mm Resolution 3.976" Base Stainless steel Buttons: power on/off, inch/mm, Preset (+,-) Battery CR2032 Data output Supplied in fitted storage case Allows you to do the following depth measurements... Depth Measurements of Small Holes ( >.157") Measure Depth of Grooves Inside Bore Measure Width of Grooves Inside Bore Includes 3 interchangeable contact points - Flat, Spherical, Disk Includes Mounting Holes for Optional Extension Bases... 7.087" Long Base # 6141-180 10.236" Long Base # 6141-260 12.598" Long Base # 6141-320