DURABLE: These versatile S-shaped spanners are made from drop forged, heat treated, chrome plated steel for durability. VERSATILE: Their S-shape design makes them idea for use in confined or awkward spaces. SIZES: With bi-hex rings, the set includes 10 sizes 10mm/11mm, 12mm/13m, 14mm/15mm, 16mm/17mm and 18mm/19mm.