bsa111 who are listing that silencer, somehow had a tie up with Brituro, who went skint. I don't know if they took on the jigs and started reproducing them or what. A couple of years back, when you typed in Brituro to Google, the links all ended up at bsa111. That one advertised looks identical to the Brituro fitted to my 400/4 but the original Brituro had a number stamped on the collector box end collar.