Jergens OK-Vise® RM Rail System Stop Risers lift our Stop Modules 28mm. The RM serration is on both the bottom and top of the block. An additional T-nut and longer bolt are included so Part No.’s RMS-S, RMS-R, and other Stop Modules will work directly on this riser block. You can use the bolt and T-nut from the original stopper in the “front” hole of the riser block.