
The Shim Kit is only required if you want to re-shim or make adjustments to the existing EF mount. The URSA Mini Pro shims are horse shoe shaped and will not work with the standard URSA or URSA Mini circular mounts. If you are looking to use the Shim Kit to reshim the URSA Mini Pro for the B4, PL or F Mount, then there is no need. Each of the Mount kits includes it's own Shim Kit.