This kit includes the sealing plate and proper screws needed to mount an RMR/SRO on the Glock MOS slide and the Springfield OSP pistol. For the SRO only the screws in this kit are required for proper mounting. One must have this kit to mount an RMR/SRO 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.