Yes they can. You can use steel pot helmet covers or PASGT helmet covers. However, these helmets use a molded foam lining instead of a suspension system. Because most helmet covers are designed to be used with real helmets that use a suspension system, you must install the covers differently than you would with a real helmet.

To install a helmet cover, simply pull out the internal molded foam liner, it is secured to the helmet with a few spots of glue. Once the liner is removed, place the cover over the helmet and tuck the excess inside of the helmet and reinsert the liner. The liner will provide enough pressure on the cover to keep it secure. Some use a small amount of adhesive tape to secure the edges of the helmet cover to the inside of the helmet.