The Power Block Sports 9.0 Dumbbells (Pair) are a component dumbbell system, giving the user the opportunity to expand the set, as strength training needs change. With a different inner core handle to the Sport 2.4 & Sport 5.0 models, Sport 9.0 Stage I Set features two 1kg 'adder weights' that slot inside the handle for micro-incremental training in steps of 1kg per hand to fine-tune exercises for greatest versatility. The weight range of the Power Block Sport 9.0 Dumbells Stage 1 can be expanded by adding the Power Block Sport 9.0 Stage 2 Kit.