The ZRO Delta The One is a modular 9mm semi-automatic pistol built around a 4-inch barrel. Rather than being sold as a stripped receiver or a partial build, it ships as a complete factory pistol with a 15+1 capacity magazine already fitted. The platform is built so the grip and configuration can be adapted to different setups, and the whole gun wears a uniform black finish across the frame and slide for a clean, consistent look.