AOP magnet socket holder is the best choose to fix sockets inserts to steel formwork if your precast concrete mold is steel. It can reuse many times. magnet socket holder need a plane surface on the steel formwork. Oil surface will protect the magnetic socket. The sockets or inserts must be thread together, then magnetic force to steel formwork or mold. The magnet adhesion area must be clean and unevenness must be removed so that the adhesion force is not reduce. Any heating of the magnet socket holderis not admissible, or the magnetic will be damaged.