This digital groove depth comparer (GDC) from Brugg measures directly within the sheave groove to identify groove variations or wear. The user lowers the gauge into a groove and allows the ball plunger to make direct contact with the walls. The first measurement serves as a set point for comparing variances in each successive sheave groove. All variance measurements are prominently displayed on the digital screen in imperial or metric units. A positive (+) reading signifies that a groove depth is shallower than the first groove measure (the initial set point), while a negative (-) reading indicates a deeper groove depth and is evidence of groove tolerance or sheave wear.