Smear the inner tube with peanut butter or honey and the P-Nut Butter Roll is an extra special treat. Monkeys will spend hours picking and licking off the peanut butter through the access ports in the outer tube. The unit clips securely to the cage and can be placed either in the cage or left hanging out for easy retrieval. Monkeys cannot disassemble it due to a monkey-proof latching system, but it is easy to service once it is unhooked from the cage, requiring no tools. If you have a monkey with behavior problems, this may prove to be the solution. Entire unit is made from stainless steel and polycarbonate plastic and will withstand repeated sanitizing.