Yes it is the real deal, good eye! I got a pretty good deal on it in exchange for a 553 I previously got for a SOPMOD II carbine. AFAIK, 553s are being replaced by the tan EXPS "SU-233B/PEQ," as the laterally mounted battery copes with recoil better, not that it matters in airsoft. It works the same, just smaller and the buttons are on the side so you can sit a magnifier closer.
The throwlever is also tension adjustable. The 553 was loose on the Inokatsu upper (but was fine on RS and Prime uppers, there goes "in spec," Inokatsu), but the EXPS mount is tension adjustable.