The Charles Daly AR .410 Upper allows any AR-15 to be converted to a .410 shotgun. The CD .410 Upper features a picatinny quad rail forend and comes with a 5rd magazine. *This upper works with mil-spec lower only. MUST USE CARBINE BUFFER TUBE. Upper includes buffer that must be used with carbine buffer spring for proper function. Overall cartridge length must be 2.29inches or less for proper function.