I have one, been running it for a year and 5 monthes, works well but the dot is not as crisp as I have seen on the Aimpoint T-1 but its fine because its for quick shooting and it does help with that tremendously. I have it mounted on a RS side mount and its low and adjustable enough to center it perfectly, I screwed around with other mounts and wasted my time trying to mount it in an ideal way and never got there till I obtained the RS mount. I have used the Ultimak but with a cheaper dot and it worked but as I used it the short commings became visible as my experience increased and both the mount and dot were abandoned. I did do a static mount with the PRO on the ultimak with a low ring and it would fit but the dot became fuzzier with extra distance from my Eye and I did not want to get my new expensive dot overheated, and optics do overheat on the Ultimak if go past a couple mags in short order. I thought there was no problem with that but doing it repeatably cooked a Primary arms micro and melted the glue holding the emitter on a TRS-25 bushnell. I understand the Aimpoint T-1 will last longer on an Ultimak with a prolific shooter but other issues combined with the heat of the Ultimak brought me back to side mounting when I obtained the Aimpoint PRO and desired to keep it working for years ....