From the website:
Within the Legio Custodes, there exists a range of ranks and seniority of commands, far from transparent to outsiders, to which the more general application of ‘Shield Captain’ is applied, though within the Legio such ranks range from Prefect to Lictor, Proconsul to Tribune, following the ancient patterns of Terra’s lost history. Elevated both through the trust held among their peers for their judgement and skill, but first and foremost advanced by the direct approval and in some cases intervention of the Emperor Himself, these are warriors not only of consummate and superhuman ability, but also rare insight, acumen and knowledge. Afforded the rarest and finest of the Imperium’s arms, each of these legendary fighters commanded the Legio Custodes against all manner of threats against the Emperor, His works and His domains.
This multi-part resin kit contains the components necessary to assemble a Legio Custodes Shield Captain. A model of exceptional detail, befitting his status as a senior commander of the Legio Custodes, every surface of his ornate power armour is broken up by rivets, plates and Imperial symbols, with the pauldrons and top plates being noticeably heftier than the already-impressive armour of his subordinates. Of particular note is the spiked and bejewelled halo above his unhelmeted head, which nicely frames the stoic scowl of leadership on display. He wears a large, flowing cloak, adding dynamic curves to the utilitarian lines of the model’s silhouette, and in his right hand wields an enormous guardian spear – from haft to point this is a truly impressive weapon. Included is a piece of rock for the base, which the Shield Captain is to be modelled standing atop.
The Legio Custodes Shield Captain comes as 9 components, and is supplied with a 40mm round base. Rules can be found in The Horus Heresy Book Seven: Inferno.