S.A.M. Park Avenue Duplex FREE 2 lb. Gourmet Hamster Food &amp; FREE 500 c.i. Pine Bedding w/ Purchase all of the s.a.m. expansion housing units become an extension of your hamster's main house all units are compatible w/ all s.a.m. toobs, most s.a.m. easy add-ons scientifically designed to work as well as it looks You can create an exciting, ever-changing environment for your pet.