USSR, from Ultimaks page...
*Will not fit, and cannot be modified to fit, any Carbines manufactured under the name "Universal" and some Carbines made by Plainfield. If you have a Universal or a non-mil spec Plainfield Carbine and you want to enjoy the benefits of the M6-B forward optic mount, it is advised that you trade it for a G.I. pattern carbine. Either a 1940's vintage or the more recent production IAI, or the new Auto Ordnance Carbines will perform better, and will be compatible with all after-market stocks and accessories.
FFMedic