Olympic and standard barbells and barbell sets for sale together with barbell covers and pads. Free weights are the best way to gain muscle mass and a barbell set should be an integral piece of gym equipment for anyone who is serious about making muscle gains.
A standard barbell can comfortably hold 120kg, which is usually sufficient for most people. However if you find you are lifting weights in excess of this weight range then you should buy an olympic barbell. Olympic barbells can hold up to 750kg of weight which is plenty even for seriously strong men!