A three piece boot comprising a sock-like inner member, a structural protective cage intermediate member incorporating rigid toe, arch and heel protection and an outer member having a sole with flexible upper with little form rigidity; the inner sock-like member having resiliently deformable foamed material bonded to the toe, sole and heel portions in order to provide a comfort liner and in order to facilitate the substitution of different inner sock-like members to accommodate a range of foot sizes within a single protective cage and flexible outer member size; a locking device to lock the protective cage to the outer member and a releasable locking device to lock the inner sock-like member into the protective cage.