These are three 28mm scale metal 1st Century Roman Officers, a Centurion, Cornicen and Optio. You cannot buy moulds for these figures. Prince August provides moulds for regular Legionaries only.
The Roman Empire's armies were one of the most famous militaries in human history. They were adaptive to the current state of the Empire so their tactics, uniforms and weapons changed depending on where they were, who they faced in combat and their history up to that point. The 1st Century CE Roman armies are perhaps the most well known to us. The army's organisation was based on Legions, large formations of soldiers that consisted of approximately 5500 legionaries.
A Centurion would be the equivalent of a NCO by today's standards and often lead his Legionaries from the front, making it a high risk rank as they were often targeted by their enemies. A Cornicen or hornblower was responsible for helping to keep order in the ranks and relay orders during the chaos of battle by using their horns to alert the ranks to change tactics. The Optio would have assisted the Centurion by keeping order in the ranks and during battle advanced behind the Legionaries he was responsible for to watch for signs of cowardice or disorder.
Download the Roman painting guide for Centurion, Cornicen and Optio here.