The Nashville Arsenal, and the 6th Mississippi, were among the first recipients of imported British military goods.  The Nashville Arsenal files shows the accoutrements to have been white buff leather Line equipment.  Made by Merrick's Custom Leather, this Cap Pocket is copied from an original, made with real buff leather, and includes a custom made finial.  Intended to be mounted to the cartridge box belt and worn on the chest, the Cap Pocket (in conjunction with the Ball Bag) was a departure from the typical American-style accoutrements.

British Cap Pocket - Shiloh