Product Description Designed for easy torque calibrations. Adapters measure 2" from the center of the square drive to the center of the adapter opening. Special heat-treated alloy steel helps to increase strength and durability. Product Reviews Write a Review Write a Review × Proto Torque Wrench Adapter 3/8Dr 13/16 Proto 5126 Rating Required Select Rating 1 star (worst) 2 stars 3 stars (average) 4 stars 5 stars (best) Name Email Required Review Subject Required Comments Required