The powerblock sports 90 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 24 and sport 50 models sport 90 stage i set features two 1kg adder weights that slot inside the handle for micro incremental training in steps of 1kg 2kg variation per hand to fine tune exercises for greatest versatility the weight range of the powerblock sport 90 dumbells stage 1