Sig Sauer is releasing a revised version of the Rattler pistol chambered in .300 Blackout. At a quick glance, we're only seeing a change to the design of the brace.
The old Rattler pistol had part number PMCX-300B-5B-TAP-PSB. The new Rattler has part number PMCX-300B-5B-TAP (UPC is 798681600182).
The new brace is a side fold version versus the telescoping brace on the old variant. The side folding version should shave about two inches on the overall length when folded versus the telescoping brace being fully retracted.
The new brace is being called a side folding PCB (Pivoting Contour Brace).
The following graphic shows the old versus new (new on top):
We don't have an ETA yet on shipping / availability but will post updates once available.