Products have been reviewed and tested by a third party testing lab for function, performance and durability. This set of Tube Bending Springs is designed to bend copper tubing without kinking or flattening the tube. The flexible spring features flared ends to provide easy insertion and removal of tubing from tool. Springs bend 1/4 in., 3/8 in., 1/2 in. and 5/8 in. O.D. copper tubing.