The Rezzin Model RZ16 Ceiling Diffuser has a round design and removable, multisize collars. The model is made of high-strength polymer resin, and is designed to fit into a round opening. The RZ16 is equipped with an integral, spring-loaded damper that locks in place after adjusting. The interlocking multiple-collar system connects to standard flexible duct sizes. The product also features a ratcheting clamp system that does not require tools when installing it to drywall or ceiling tiles.

Hart & Cooley Inc., 500 E. Eighth St., Holland, MI 49423; (616) 392-7855; fax (616) 392-7871; www.hartandcooley.com.