Weight plates are great for weight training and can be used with either dumbbell handles or barbells. They come in a wide range of weights from 0.5kg upwards. In order for your dumbbell or barbell to be equally weighted, you would typically need weights on either end of the bar to be of the same size so for example, if you placed a 7.5kg weight plate on each end of your barbell, then you would be lifting a total of 15kg plus the weight of your unloaded bar. When purchasing weight plates, it is important that you get the right type of plates for your bar. If you have a standard one inch bar, then you should buy standard one inch weight plates. These have a hole in the middle that is just large enough to fit on the end of your one inch bar. Similarly, if you have a two inch, or Olympic bar, then you would need Olympic, or two inch plates. Clearly, if you try using one inch plates on an Olympic bar, the weights will not fit and if you try using Olympic plates on a one inch bar, the hole will be too big and they will be unstable and dangerous to use. To secure your weight plates on your bar, you will also need a pair of collars, one for each end. These will keep the weight plates securely in place while you workout.