The H&Y Revoring is a variable stepping ring that lets you attach larger filters to lenses with a range of smaller filter threads- handy if you're trying to share a single set of filters among several different lenses. As a bonus, these will let you use standard-sized filters on lenses with non-standard filter rings, as long as they're in the range of adjustment of each Revoring. A well-made, all metal accessory with strong spring action.

The sizes of each Revoring are given as a range of compatible sizes: the smallest is the minimum compatible lens diameter, and the largest corresponds to both the maximum lens diameter and the filter size on the front of the Revoring.