OK.  So what are the benfits of the 553 model other than the lever mount and 123 batts.  Is there an AA version or is the 123 batt veresion the only version?  release date?

this is from SWFA.com

New EOTech 553 Military Holosight    

The EOTech 553 has been upgraded to submersible 66 ft. water depth. Within this same feature upgrade, the membrane pad has been redesigned to greatly improve the tactile feel of the push button switches. The switches are designed with raised inlays to provide further separation between switch controls and reduce audible signature.

Compatible with Gen. I-III+ Night Vision Systems (tandem operation)
Interfaces to standard 1" Weaver dovetail/Picatinny rail
Factory pre-mounted with 2D Standard reticle pattern
Specifications
Optics: Transmission holography - 100% parrallax
2D

Magnification: 1x unlimited eye releif
Length/Width/Height: 5 x 1.8 x 2.25
Field of View @ 100yds (ft): 3.8 - 3.1
Weight (oz): 11.5
Temperature: -20 to 150F (operating); -40 to 160F (storage)
Sealing: Waterproof (submersible) & Fogproof
Color/Finish: Non-reflective black with hard coat finish
Adjustment (per click): 0.5" at 100 yards
Adjustment Range: +/- 40 MOA travel
Mount: 1" Weaver Dovetail / Picatinny rail (Mil-Spec 1913)
Return to Zero: Repeatable to 1 MOA after remounting
MOA: 1
Warranty: 2 Years
Heads-Up Display Window
Optics Surfaces: Anti-glare and scratch resistant coatings
Window Dimensions: 1.20" x 0.85" (30 x 23 mm)
Window Material: Shatterproof laminate (3/16" thick)
Field of View @ 100 yards: 30 yards (28m) at a 4" eye relief
Standard reticle: 65 MOA ring with quadrant ticks with a 1 MOA Aiming dot
Reticle Contrast Ratio: 28,000:1 brightest to lowest
Night Vision Contrast Ratio: 10,000,000:1 with NV switch engaged
Electrical
Power Source: 2 x "AA" alkaline batteries (available anywhere)
Battery Life: 350 hours at normal setting 12
Brightness Settings: 20 settings with scrolling feature
Auto Battery Check Indicator: Flashing reticle upon startup if batteries are at 20% of battery life
Auto Shutdown At 8 hours - programmable to 4 hours