This kit includes the sealing plate and proper screws needed to mount an RMR(R)/SRO(TM) on the Glock(R) MOS slide and the Springfield(R) OSP pistol. For the SRO(TM)" only the screws in this kit are required for proper mounting. One must have this kit to mount an RMR(R)/SRO(TM) on a MOS slide. Both optics ship with two long screws which will NOT work. You will need the two short screws in this kit.