Plastic Finger Sizer for Ring Sizing This inexpensive plastic Finger Sizer work just like a belt. Simply push the end through to form a ring shape, then slip onto finger. Adjust to a comfortable fit that slips over knuckles, then read the indicated size. Finger sizer features measurements 1 to 17 in 1/4 size increments. Overall length: 5", Size measurements: 1-17