OPF-G, RMR does not require a sealer plate. In service since March of 2020, OPF-G, RMR, it's been carried by officers that wade into rivers, ponds, and muddy water, there has never been any instance of water intrusion.
Our position is adopted from Trijicon's on sealer plate: though it's not required on our plate, it won't hurt if you do decide to install it, especially if you are taking it in a dive.
This post from ar15.com is quite telling (thread can be found here: https://www.ar15.com/forums/handguns/MOS-owners-get-in-here--Better-plate-system-inside-/13-188416/&page=37
Just wanted to mention this story, as some of you might find it useful
agency now has about 30 RDS-equipped handguns, issued to our SWAT team
and training unit. They are issued guns--G17.5 MOS with Trijicon RMRs
and FCD plates, with no sealing plate. We have had them in service now
for about 6 months.
A few days ago we had a call-out. One of our
snipers took up a position of cover in the prone position at the edge
of a dirt road. A short while after deploying it started to rain--hard.
Within a few minutes he was laying prone in a puddle of moving, muddy
water, with the top end/sight of the handgun submerged. After lying in
the puddle for about an hour and a half the call-out was resolved.
Immediately after the debrief he started cleaning up his equipment. So
much water/mud/dirt had collected in the holster that the deputy had to
force the hood forward to draw his handgun (he advised that he didn't
believe this was a deficiency of the holster, and believed any holster
would have had similar problems in that situation).
thorough exterior cleaning of the handgun he called me and asked if I
would like to take it down to an armorer's level inspection, and to
check the RMR to make sure there were no issues. I felt this was a
great opportunity to check the 'weatherproofedness' of the sight and
plate. I am happy to report that there was no intrusion of
water/dirt/debris in between the sight and plate (remember, we are not
running a sealing plate). Also, just as an aside, the operator
mentioned that, while the sight had been submerged in water for over an
hour and there was visible water on the sight/glass and some
'starburst,' he would have had no problems using the sight, if
Anyway, just anecdotal real-world report.
With the seal plate installed, the RMR can be submerged up to 66ft. for at least one hour without leakage.
Made from stainless steel and weighs 2.8 g.
Compatible with the all Trijicon manufactured RMR pistol mounts.