For Sale, optima 2000 with custom ACOG NSN mount. Unit replaces the rear peep sight, allows use of 4 scope and close up cqb capability. KAC makes one unavailable to the public for HRT, this one is the same as revieved on this board. Not many out there. Great condition, new battery, with optima manual and hood. $200 shipped or trade for Q3131a or xm193. Optima sights alone selling on ebay now for 180+.