First fitting of a keel-based foot requires shell, insole and sock together, which a set supplies at once.
Shoe fit depends on the shell and insole together, since both contribute to how the assembly fills the footwear.
Users reporting movement inside the shoe may be helped by insole thickness, which affects how snugly the foot sits.
Users troubled by noise from the prosthesis are addressed by the sock, which damps keel movement within the shell.
Shell surface life is extended by a sock, which takes abrasion from the shoe lining instead.
Replacement cycles differ between the components, so individual availability matters to a clinic holding stock.
Keel compatibility is determined by the shell, which must accept the module in use without restricting its flex.