Cheap chinese junk with too much play to be usable, even if it doesn't fall apart on you - NCSTAR Flip to Side Magnifier 30mm QR Mount

All the review that claim this has too much play, slop and wobble are correct. The ting is assembled so loosely it's unusable for using as an optic mount. The button function is pretty cool, and it fits my Primary Arms 3x magnifier, but there's a minimum 1/8" play in every direction when it's "fixed" into place, so you're always seeing the edges of your red dot or other optic's body when you're trying to look through your magnifier.

Here's the real deal breaker though. After having used this for no more than 10 shooting sessions on my AR in .22LR, the thing fell apart and my 3x magnifier along with this POS fell right off the rifle. On inspecting it closer, the metal pin that locks the mount into the 1913 rail slots (which should have been pressed or welded into place) was missing. Apparently it fell off due to all that .22LR caliber recoil! It was no where to be found.

I would have given it 2 stars, if it weren't for the worthless warranty. 1 year limited warranty on ncStar accessories. Except if it's past 90 days you have to pay them a $10 handling fee, so for a $23 Chi-Com disposable junk product, which turns out to be essentially worthless, the warranty is just as useless.