The TLR Race Team has been fine tuning the front roll center of the 22-4 by adding spacers under the ball stud of the castor block. The stock TLR Ball Stud Spacers have a larger OD which interferes with the 22-4 front castor block. To help clear the castor block properly, TLR has now introduced the 22-4 Caster Block Alum Ballstud Spacers (4ea).