Used with a QRP2/TNP/LRP mounts, this rises the 30mm optic to 1.55" above the Picatinny rail, and is needed for flat top AR type receivers. 1.55" is higher than absolute co-witness, but lower than 1/3 co-witness, but is the desired height for most M4 / AR15 applications with Aimpoint.
Includes wrench and two screws.