Eotech 553
Eotech’s 553 (military version) takes CR123 batteries which are now commonplace, for an advertised battery life of 1100 hours at nominal setting. The two CR123 batteries are housed in a battery compartment that is tethered to prevent loss. Finish is flat dark earth, a USSOCOM colour (in which the Vltor and Tangodown furniture below are available in as well).
A great improvement over the single screw mount of the previous versions are the A.R.M.S. throw levers. I don’t find them to be obtrusive in any way, on the left side. The 553 is also about .25″ higher than the 551. I found that the 551 sits a bit low on a flattop, and adding a .25″ riser gives the best cheek weld. The 553 addresses that issue, and puts the window/reticle at the right height now. It also co-witnesses the irons in the bottom 1/3 of the window instead of centering it vertically, also an improvement.