I see a lot of pics with the closed, scope style sights. Anyone ever have any luck with an open reflex sight like this one:

http://www.tactical-life.com/online/...tal-switch.jpg

I'm interested where to get the "clamp" device that makes attaching and removing the sight quick. What are they called? Available aftermarket?

That Sightmark is the same one I'm looking to get, I did a search n found 5 pages of only some info, mostly a lot of people switch to the scope style red dot.....

And the attachment to rail is by the quick detach or "QD" .... Yea I believe a few company's sell those out right...

Quick detach mounting system, and that unit includes the mounting hardware

I prefer the reflex sight or aimpoint type micro sights on my .22's.
That sightmark sight in OP looks to be a good option.

Most people who use their AR15-22 for speed shooting use reflex sights. They have a distinct advantage when shooting with both eyes open. Mainly the ability to see the next target quicker than a tube red dot. When using a tube red dot you would need to put it farther away from you on the rifle to get the same effect.
Before the advent of the higher end reflex sights like the C-More and OKO most speed pistol shooters used 50mm tube red dots. However once reflex sights became available it was found that only about a 30mm window on a reflex sight was needed to mantain target transitions.
A lot depends on what you are used to and like to use. Aimpoint Micros are prefered by some shooters. I use mostly C-Mores myself because I take my match performance seriously.

The one on the Sightmark is part of the sight. It comes 2 ways, with and without the QR mount.

i use C-More railways on all my .22 pistols (MKII race and a not so race MKII and a buck mark) on the M&P i run a Vortex strike fire bright dot with a primary arms 3x in FTS mount for bunny hunting. 10/22's all have high end adjustable glass on top since they went from $200 rifles to $1200 rifles in just the flash of a credit card!
Love the C-More though...right on target....fast, no tube to look for dot in as i had to do with others. plus you can get different sized dot diodes that go from IIRC 3 MOA to 16 MOA. I usually run a 4.