Tiffen838SSLR to 4.5" Adapter Rings, sometimes referred to as Step-Up Rings, are mounted directly to the front thread of the lens and provide access to a universal or larger-size round drop-in filter. It should be noted that to facilitate the use of drop-in filters on threaded and unthreaded lens barrels, Tiffen also uses the Set-Screw-Lock Ring Adapter (SSLR).