APS Creatine Monohydrate
Creatine is a staple supplement when it comes to putting on muscle mass.
Creatine allows you to workout at your maximum effort longer. If you can bench 315lb for one set of three and you start taking creatine you should be able to do it for two or three sets of three.
Creatine works by regenerating ATP (energy in the body) which allows maximum effort for a longer period of time.