Shaft Extenders fit into the butt of the existing shaft and underneath the grip to extend clublength. This graphite shaft extenders fits many lighter or thinner walled graphite shafts. The 0.535" dimension is the outside diameter of the part that goes into the shaft. If the stem is too large, it can be sanded as much as 0.020". The upper portion that goes above the butt of the shaft measures 0.600".