308-002 12.5" Deep Throat Thickness Gage12. 5" Deep Throat Thickness Gage 0 . 400" Measuring Range This gage includes a 0 . 4 measuring range with a 0 12. 5 deep reach, allowing you to measure thickness in hard to reach places. Also included is a 4" Adjustable Post that allows you to measure thicknesses of material that is up to 4" thick. The attached lifting lever makes for one handed operation, and the included Dial Indicator includes the following specifications 0. 0005" Graduation 0 0.