6311 | Teng 11Pc Double Ring Spanner Set (MM) 11 piece metric double ring spanner set ranging from 6x7mm to 20x22mm. Each spanner features different bi-hexagonal openings at each end. All of the heads are offset by 75. The spanners are supplied in a coloured display box only. Double Ring Spanners Sizes: 6×7 8×9 10×11 12×13 14×15 16×17 Double Ring Spanners contd. Sizes: 18×19 20×22 21×23 24×27 30x32mm