Laserlyte mini boresight - LaserLyte Universal Laser Bore Sight

The spud has a little screw and a plastic 'doohickey' on the end that you adjust to get a non-wobbly fit in the bore. I only sued the smallest doohickey. A slight adjustment - 1/8th of a turn - makes all the difference between an unacceptably loose fit and an unnecessarily tight fit (be careful and don't loosen/tighten it when in the bore - otherwise, you are asking for trouble).
The on/off switch is fiddly, but go easy with it and you will be able to turns the thing on and off.
I was disappointed with the laser spot size at 25m - it is around 3" diameter! As a consequence, the boresighter was not useful for sighting in a 3-9x scope - it will get you on the paper, but that's it.
Think about it, I expect to put all my shots within a 1/4" with a 1 MOA barrel at 25 yards. A 3" diameter circle at 25 yards corresponds to 11.4 MOA (top to bottom) and on most scope, (1/4 MOA/click), 44+ clicks!
The spud is long enough that I had no problems on an AR15 with the standard A2 flash hider. I also used it on a 5.7mm rifle with a 1.5" long flash hider with no problems.

Pros: Works in ARs
Cons: Fiddly switch

This review was written in the old system and had content requirements that are different than reviews written today.