This mandrel can be installed on the Ruger Moon Clip Loading Tool (#18751) to simplify loading and unloading of rounds in the moon clip. It is made of aluminum and is .510” in diameter. This mandrel is designed for use with TK™ Custom Moon Clips (#18733) for the Ruger GP100 Match Champion, 40 S&W, 6-round . Made in the USA by TK™ Custom.