The RMR sealing plate is laser cut, 0.125" thick stainless steel and black oxide coated, the sealing plate is made for Trijicon's RMR sights.
The only FCD RMR plate that requires a sealing plate is the OPF-S, RMR (Staccato) due to its lightening cut.
OPF-G, RMR, OPF-PDP, RMR, OPF-P320, RMR, and OPF-FN509T, RMR do not require a sealing plate.
Proudly designed and made in the USA.