A binding member, including a first disk ring portion configured for reception in a binding recess of a sheet member. The first disk ring portion can have an inner surface that faces radially inward for engaging and retaining a first binding protrusion of a sheet member for binding the sheet member. The first disk ring portion can be configured for allowing the bound sheet members to slide around the first disk ring portion while retaining the engagement. The binding member can also have an axial extension member associated with the first disk ring portion and extending generally in an axial direction with respect thereto.