Now you can convert your AR-15 or your M16 into the most suitable optics platform by using the newly designed Weaver Thumbnut Flat Top Riser Rail - AR15 / M16. This design has multiple slots, which give you myriad of options when you are setting eye relief. The riser rail is constructed out of aircraft-grade, 6061-T6 aluminum. The final product has a durable finish made of black matte. The product is engineered to ensure optimal mounting height for any ring and optic combinations. There is also a new thumbnut feature, which provides for fast and reliable detachment and installation sans tools.