Four tapped holes to accept replaceable bushings Self-centering 2" capacity The model 2500 features four tapped holes to accept replaceable drill bushings. This will allow you to drill a multiple combination of holes using various hole sizes of your choice. The jig does not have to be moved in order to accomplish this, and is therefore more accurate. This jig comes with 6 removable bushings, 2 of each size: 1/4", 5./16", and 3/8". The bushings and jig center block are precision hardened and plated for rust protection. The rugged aluminum sides will hold your work securely in place without damage to the wood.