52 - 55mm Step-Up Ring allows users to attach a 55mm lens accessory (such as hoods, flashes and lens converters) or filter to a lens with a 52mm filter mount size. The adapter ring is made of metal and is a mere 6mm thick.
The Step-Up Ring is a reliable and economical way to use filters. Using this ring saves you money since you wont have to buy the same filter two times for two different sized lenses. For example, a 49-52mm Step-Up Ring would allow you to use 52mm filters on lenses with a 49mm front filter thread size. A series of these reasonably priced adapter rings is far less expensive than buying the same filter in two sizes.