This is a used Atlas Front sight block picatinny/M1913 rail adapter. It is suitable for mounting flashlights, and/or lasers to the A1/A2 front sight block of your rifle. It may also fit airsoft rifle with similarly designed front sight bases. It solidly clamps to the front sight using a 3/16" allen head machine screw with included allen wrench. These are precision machined for a secure fit so that it won't rotate to twist out of alignment during heavy firing sessions. This came on one of my AR-15 uppers, and I don't need it anymore. It will fit with standard carbine style handguards, as well as Magpul MOE handguards. (it will probably fit with most all handguards, I only have experience with those two) It features 1.75" of rail space on both sides of front sight. Made of aluminum and black anodized. The mount show normal signs of wear, but nothing out of the ordinary. Please email or call/text 406-five four four-8258, if I don't answer, please leave a message and I will get back to you.