Use the Weaver Optics Thumb Nut Flattop Riser Rail for AR-15/M16 to achieve optimal eye relief and height. This multi-slot flat top riser is designed for AR-15 and M16 platforms, and features a lightweight and durable 6061-T6 aluminum construction. To help you mount it without any tools, the riser has two finger-operated thumbscrews.
I recently received my order and, after inspection, figured I'd leave a review. The riser appears to be well made with even anodizing and no obvious pitting, no other cosmetic defects. The rail itself seems to be very slightly oversized in regards to the m1913/Picatinny specs, although I doubt this would be a problem with a standard scope ring that would allow for some variance. I could see this as an issue with a BUIS such as Magpul or other polymer sights that slide into place. The only real complaints that I have are that the mounting screws are not done in the standard press fit fashion. They are actually threaded on both ends and threaded through the fixed side of the mount as opposed to using an oversized head that is press fitted. In theory, this could allow the screws to pull through their threading if someone were to tighten the thumb nuts down too tightly. Also, on the thumb nut end the screw heads are not staked into place which could allow you to inadvertently drop a thumb nut and lose it. All in all though, I'm satisfied for the price that I paid.
Area in front of front screw attach. Would not clear 2 1/2" handguard