Twelve piece combination spanner set have two heads: one with an open-ended profile and the other with a ring profile. The two heads are usually the same size and range. A spanner works by gripping a nut or bolt and twisting it clockwise or anticlockwise to tighten or loosen it. Tata Agrico Combination spanners are made from chrome vanadium steel. Chromium and vanadium are metal elements that are added to steel to increase the metal's strength. Chromium also increases the steel's resistance to rusting. The available spanner sizes are: - 6mm, 8mm, 10mm, 12mm, 14mm, 16mm, 18mm, 20mm, 22mm, 24mm, 26mm and 30mm. Combination spanners are good value for money as you get two tools for the price of one although remember that both the heads are the same size so you only get one size per spanner. LxWxH: 39X11X9 (cms) Weight: 2kg