/ Precision Measuring Tools / Precision Hand Tools / Depth Gages / Depth Gage Accessories / 648-4 * Not actual product image 65850 648-4 Depth Gage Base with Stem Collet 65850 Other similar products 4" long depth gage base with 25SC38 Stem Collet to fit 3/8" (9.5mm) stem diameter (as per AGD). Features Contact Starrett Features Additional tapped holes for special collet positioning. Hardened Steel. 3/4" wide base.