This is designed to fit around the standard bayonet lug found on AR15, M4, and M16 rifles. It will also fit post-ban front sight bases without a bayonet lug.
No, this will not be compatible with optics ready models of AR15's as they do not have a standard A1 or A2 front sight base (FSB).
The thumb screw option has a code number that ends with a "T" and has a slightly higher price. Example - Code:29L-1F-TFMT-ZFH1500B-T
It will most likely not fit properly without removing the portion of the handguard that covers part of the front sight post/gas block. This would be a permanent modification so we do not recommend.
It clamps around the standard A2 style front sight/gas block. I did a quick search and it looks like Ruger is using a slightly different front sight, but not quite the same, so I doubt it would fit. It should fit any other value-priced AR-15, though.
This fits over the standard A2 style front sight. It will work with or without a bayonet lug.