3P10 a 5/8 x 24, 30 cal Plan B compatible flash suppressor / sound suppressor mount, a collaboration is  between Revival Defense https://www.revivaldefense.com/ and Forward Controls Design.
Unlike our tried and true 6315 design that provides both effective flash suppression and muzzle rise compensation, 3P15 (1/2 x 28) and 3P10 (5/8 x 24) are both pure flash suppressors that support Plan B and Atlas adapters.
3P10 is both a precision suppressor mount for Plan B and Atlas compatible sound suppressors and a superb flash suppressor. Our design philosophy regarding suppressor mounts is that in addition to their ability to mount the suppressors for which they’re designed, they should be good flash suppressors, compensators, brake, etc. in their own right  3P15 is shorter and smaller in diameter than many suppressor mounts/flash suppressors, these dimensions are defined by compatibility with Plan B and Atlas adapters. Given these constraints, 3P10’s flash suppression is very good, compared to A1, A2, and other similarly dimensioned open ended flash suppressors.
3P15 had 4 revisions, 3P10 had 5 before we were happy with their performance. They are Plan B / Atlas compatible flash suppressors / suppressor mounts. Here’s a pic that shows a bit of the 3P10 prong and the internal grooves. The width and depth of the flutes on the exterior of the prongs were designed to both reduce weight, and give each prong a different mass so they don’t conspire to work as a tuning fork.
The internal grooves serve to improve gas expansion and cooling, but by themselves, they’re not sufficient to make the device a better flash suppressor. Distance between each prong, the shape of the opening, the bore size and the length of the prongs are all factors.