Dennis, The problem with the Instapak packs is with heavier items it has no memory i.e. each time it is dropped the weight cause the foam to settle and no rebound like Ethafoam. It has a density of .40 lbs per Cu ft. so anything in excess of about 50 #'s will cause it to deform. Hank KN6DI Global Pack & Mail 23 years in packing business.