Perfect fit - TRYBE Defense Smith & Wesson M&P 9mm 4in M2.0 Match Grade Threaded Pistol Barrel

It dropped right in to the m&p 2.0 compact- unlike the more expensive Faxon barrel which did not fit at all and was going to take a gunsmith and probably cost more money than I spent even buying the gun, and it definitely came with the O-ring on it, which a lot of people were saying it wouldn't on line.