URREA 3700M Full Polished Flare Nut Wrenches, Set of 5 Pieces, Metric Wrenches sizes included: 9 x 11mm, 10 x 12mm, 13 x 14mm, 15 x 17mm, 16 x 18mm. Set of 5 pieces. This unique design is mainly used in repairs and maintenance of refrigeration systems, where often times the nuts or couplings are made from soft materials, thus the importance of having a perfect fit, to avoid damaging the parts. They help tighten or loosen pipe joints made mainly with soft metals, like bronze, copper and aluminium. They have an ergonomic geometry that improves grip and fastening since their openings are precision-cut.