These are new made SMG spec. Uzi barrels that has had the front of the barrel shortened so the barrel length is 8.5″. These are known as FBI or Secret Service Uzi Barrels. They required shorter barrels so they would fit in their Samsonite cases. They are the only barrels currently on the market that are made to IMI prints. They are 1 in 10″ twist 9mm barrels that are machined then parkerized as called for on the IMI print.
All NFA rules apply. These barrels can only be legally used in a registered machine gun, registered Short Barrel Rifle (SBR) or a pistol. They can not be used in a standard carbine with a 16″ barrel unless you register your carbine with ATF NFA as a legal SBR.