two twin - sheet thermoformed thermoplastic sleeve halves engage within peripheral grooves in an underlying pallet and an overlying cover . each sleeve half has a full wall which is connected by integrally thermoformed hinges to two partial walls . the integral connection between the sleeve walls gives advantageous rigidity to the pallet sleeve assembly , while the hinging of the walls allows economical manufacture and low volume flat storage of the sleeve halves in a knocked - down configuration . the hinges preferably have non - specific hinge axes , thereby providing long hinge life , impact resistance , and ease of operation . vertical substrate tubes are totally encapsulated into each sleeve half to carry loads from a supported loaded pallet sleeve assembly . to effectively transfer the loads from the cover to the sleeve , sinuous transfer ridges are molded on the sleeves above and below the vertical substrate tubes . the transfer ridges are positioned directly beneath the cover reinforcing substrate to maximize the assembly &# 39 ; s load supporting capability . the upper projecting lip of the sleeve is positioned to tend to cause the sleeve to bow inward , where interaction with the pallet contents contributes to overall stiffness . the pinch areas between the inner and outer sheets of the sleeve are preferably oval .