Sig P35 Fuse with Romeo-X Compact (with MAGNETAC™ (Magnetic Activation).
I was able to secure two circular Neodymium magnets to a good location that would actually turn off the optic. I used JB SuperWeld Light Activated Glue with excellent results.
As you can see in the pictures, the magnets over hang the holster, but do not interfere with drawing or holstering the firearm.
