Round Ring Sizers are used to measure any SilverRing™ Splints that use round rings (Stable Thumb, Pulley, Buddy Rings. 2 1/2 Buddy Rings, Trigger, Dorsal Extension and EDS). This tool is the same way jewelers measure for all normals rings for the fingers and thumb. Our standard Round Ring Sizers can measure from size 1.0 to 15.0. If larger sizers are needed think about visiting a local jewelry store or contact us for help.