These BD spurs mount onto the front side of bass drums and are used to anchor the drum , and decrease sliding forward when being played. Mounts with 3 holes in a triangle pattern. Slightly lighter than the others we sell. This model's left and right spurs are interchangable with each other( both sides are the exact same part) The hole spacing for these spurs are as follows: There are three holes total. The bottom two holes are spaced 2 3/16" apart from each other. 2 1/8" is the measurement from each of those holes to the top hole on the mounting plate.