If anyone is looking for an excellent stand alone rear sight, RRA has just knocked $20 off of theirs. Purchase price is now $90 instead of $110. I just bought my third one and think it is the best milspec style sight on the market - even better than the LMT, which sells for $135. The RRA unit has two clamp screws instead of one and they are much neater looking without the usual huge clamp knob of the LMT and knockoff units. Here's the link.
https://www.rockriverarms.com/index.cfm?fuseaction=category.display&category_id=320
https://www.rockriverarms.com/index.cfm?fuseaction=category.display&category_id=320