SE JT147RS 16-Piece Ring Stretcher Set Total of 16 rollers: (10) V grooves + (6) U grooves Reversible base plate with 16 total reduction dies Stretches/reduces ring sizes (1 to 33) and bands up to 12mm Dimensions: 17-1/2 x 4-1/4 x 7-1/4 Stretch and resize your stone set rings