OPF-FN509T, RMR is a solid state (one piece), steel plate designed for the FN 509 Tactical and FN 509 MRD.

LAPD is perhaps the largest LE agency that adopted and authorizes the FN 509 Tactical, the authorized version is FN 509 MRD-LE. They wanted to see if they can improve on what came with the gun. 

OPF-FNT09T, RMR is a one piece, billet machined plate for RMR/SRO, it is not guaranteed to work with non-Trijicon sights that have the RMR footprint. The way FN has designed the optics plate for the 509 Tactical is rather unusual to them, it consists of a MIM or cast steel plate with lugs for the RMR, and a larger plastic piece sans any lugs or means to prevent the sight from moving laterally. This isn't a criticism for the FN design, they prefer a solid state design without moving parts. 

OPF-FN509T, RMR is designed and made like other OPF plates that came before, with tight tolerances between the plate and slide, and between the optic and plate. Factory FN 509 Tactical sights remain compatible with OPF-FN509T, RMR and provide lower 1/3 co-witnessing. 

OPF-FN509t, RMR is shipped with a T10 key, a packet of VC-3, two 6-40 x 1/2 T10 screws (also available separately). FN 509 Tactical's optics plate arrangement is rather curious. The 6-40 x 1/2 T10 screws are the only screws used, which are installed from the top of the sight, go through the mounting plate, and into the slide. 

OPF-FN509T, RMR includes the adapter plate, two 6-40 x 1/2 T10 screws (same spec as the plates/screws packet included in the 509 Tactical, the FN supplied screws also work on OPF-509T, RMR plate), a packet of VC-3 thread locker, and a T10 key.  A proper torque wrench is required to impart the correct torque value to the mounting screws.

Torque value for the 6-40 x 1/2 T10 screws is 12 to 13 in lbs. 

Proudly designed and made in the USA.

Please NOTE:

• Trijicon's new RCR and RMR HD are both compatible with OPF-FN509, RMR.  If you have an RCR, you must use the capstan screws that came with the RCR.
• OPF-FN509T, RMR is not compatible with 502 and Reflex.