Looks like G9 bullets - makers of solid brass rifle bullets, are now going to manufacture loaded pistol ammo, and they are loading a custom lathe-turned solid copper bullet (because who isn’t these days) which they call the external hollow point / (EHP™). It is basically a solid copper version of the polycase “ARX” and Lehigh “Extreme Defender” combined, and is just another in the recent growing line of computer-designed cavitation fluid-disruption projectiles like the ARX, the Lehigh Extreme Defender, and the Lehigh cavitator - or the THV and Devel bullets of old.
On the G9 website they show a few calibers which will load this custom bullet, but only have real photos of the 9mm version. They also show a listing for the Full-Stop hollow point, which is an L-Tech & American Reserve Munitions produciton, so that is odd, unless they are buying the Fullstop bullet from L-Tech and loading their own branding of it in the same way which American Reserve is, which would rule out American Reserve having any kind of exclusivity on that projectile I guess.
Listed at 80gr and 1480 fps, this thing will be a potentially serious penetrator.