Glock with a Holosun optic mounted on the Tier One Tac co-witness plate
Buy on eBay

Optic plate with a built-in rear sight.

Mount a Holosun 509T or AEMS Macro on your RMR-cut slide and keep a usable rear sight. Your irons co-witness through the optic.

Buy on eBay · $75Check fitment →
TOT-01 · $75
Co-witness optic plateRMR cut · 509T · AEMS Macro
Engineered for precision

One plate. Two jobs. No new slide cut.

Tier One Tac builds the parts we wanted on our own pistols and couldn't find. This plate adapts an RMR-cut slide to a closed-emitter Holosun and adds a rear sight at co-witness height. If the dot goes down, you still have a sight picture.

See the plate →
Tier One Tac optic plate on white showing the integrated rear sight notch
The plate · TOT-01

Co-witness optic plate

$75
Slide cutTrijicon RMR footprint
OpticsHolosun 509T
Holosun AEMS Macro
Rear sightIntegrated U-notch
Sight heightCo-witness
Buy on eBayAsk on Instagram →

Not sure it fits? DM @tier.onetac with your slide and optic before you buy.

Sight picture through the optic: green dot above the front sight, framed by the plate's rear notch
Dot up top. Irons underneath.
The co-witness

Lose the dot, keep the sight picture.

The rear notch is part of the plate, so it sits right under the optic window. Your front sight lines up through the glass every time you present the pistol. If the battery dies or the lens fogs, your irons are already there.

Rear view of a pistol with the optic mounted, spare plate on the mat

Will it fit my setup?

Pick your slide cut and your optic.

01 · Your slide
02 · Your optic
03 · Result

Pick both

Your answer shows up here.

Mount it in four steps

No gunsmith, no new cut. Just the plate, your optic and a torque driver.

  1. 01Remove the cover plateTake the factory cover plate off your RMR-cut slide.
  2. 02Seat the plateSet the TOT plate into the RMR cut and torque it down.
  3. 03Mount your opticInstall your 509T or AEMS Macro on the plate.
  4. 04Confirm co-witnessLine up the front sight in the rear notch, then zero your dot.
Follow the build on Instagram@tier.onetac Shop the plate on eBay$75 · Ships from SoCal

Questions

Which slides does this plate fit?

Slides cut for the Trijicon RMR footprint. If your slide has a different optic cut, this plate is not the right fit.

Which optics can I mount on it?

The Holosun 509T and the Holosun AEMS Macro.

What does co-witness mean?

The integrated rear sight lines up with your front sight through the optic window. If the dot goes down, you still have a usable iron sight picture.

Do I need a new front sight?

Send us your pistol model and current front sight and we'll confirm before you order.

How do I buy one?

The plate is $75 on our eBay store. Questions first? Message @tier.onetac on Instagram.