NCStar's Gen2 AR15 Riser raises your Picatinny rail platform by .75" which aids in getting low profile optic mounts to a more comfortable cheekrest height and shooting position. It mounts onto the Picatinny rail of your AR15/M4 receiver by a locking Quick Release, which allows you to quickly attach and remove your optics and maintain zero. The Gen2 model has an updated shape, a locking Quick Release mount with shorter lever, and is lighter than the previous version. A see-through channel below the rail keeps the mount lighter, and allows you to use factory iron sights. Features: Gen-2 AR-15 3/4 inches riser, raises your Picatinny rail platform by 3/4 inches, helps with getting low profile optic mounts to a more comfortable cheek rest height and shooting position Mounts via a locking quick release mount onto your Picatinny rail of your AR-15/M4 receiver, you can quickly attach and remove your optic from your receiver and maintain your zero There is a see through channel below the rail to keep the mount lighter and for some firearm types, it may allow you to use some factory iron sights