Fortis Manufacturing, Inc., Night Rail, 12.875" Free Float Handguard, KeyMod, Fits AR-15, Black WARNING: This product can expose you to chemicals including arsenic, which is known to the State of California to cause cancer. For more information, go to www.P65Warnings.ca.gov Material: Aircraft Grade 6061-T6 Aluminum / Barrel Nut: 4140 Steel Proprietary, patented 2 piece barrel nut that provides 360 degree contact Free float rail design M-LOK attachment points No visible screws on the rail system Will include (throw away) barrel nut wrench to install 1.35" Internal Diameter Made in the USA! When designing the Night Rail, Fortis wanted to design a handguard that was easy to install, but also to be able to mount with a full 360 degrees of contact. Their new patent pending, two piece barrel nut is one of a kind. Fortis developed it from the ground up and the machining time it takes to make the barrel nut, rivals the time making the actual rail. That's not to say the rail is simple to make. One look and you'll see that they really took time with this in design and development. What they ended up with is a rail that not only looks amazing, but is still true to Fortis' lightweight brand. The barrel nut/mounting system keeps the rail performing even during the harshest of conditions.