Type-56 Crystal Magnifier

This attachment is analog to the UNSC's reflex sight, but it can magnify up to 12 times. Also sticks to any Sangheili weapon.
Primary Mode - doesn't magnify, but allows a clearer view on a target.
Secondary Mode - magnifies 4 times.
Tertiary Mode - magnifies 8 times.
Quartiary Mode - magnifies 12 times.
It uses a rare crystal mined in the depths of Sangheilios, which is a dangerous job to have. The crystal is in a unusual state of matter, a semi-solid. It generally acts as a solid, but becomes flexible when subject to the right amount of pressure. 
This attachment is only issued to Special Forces, or to anyone able to afford one.