The Blue Spot Tools 5 PCE Flare Nut Spanner Set (9-21mm) is designed for use with compression nuts on hydraulic lines, diesel and petrol injectors, gas and refrigeration systems. The flared design enables you to overcome the line where a traditional spanner would fail. The spanner has a greater surface area once in situ. Manufactured from chrome vanadium, heat-treated and nickel-plated for increased durability. 15? Jaw Manufactured from chrome vanadium, heat treated and nickel plated for increased durability For use with compression nuts on hydraulic lines, diesel and petrol injectors, gas and refrigeration systems