This is a used LaRue LT110.
The LT110 raises the EOTech by .275". This extra height sticks the irons low in the EOTech's window...you can still see the irons if push-comes-to-shove.
NOTE: The LT110 EOTech Mount will work correctly with 511, 512, 551, 552, XPS-2, XPS-3 and similar models. It will NOT work with the EXPS2 or EXPS3, it also will NOT work with 516, 517, 553 or 557 models (or any EOTech with a built-in riser). The LT110 is not compatible with an EOLAD installed.