1. It is suggested that the initial training intensity is 5-7.5 kg for biceps brachii, 2.5-5 kg for triceps brachii with dumbbells, and 1-handed shoulder 10 kg. So it is just right to buy a pair of dumbbells with a nominal weight of 30 kg (actually only a little more than 20 kg) at first.

2. There are also adjustable dumbbells in the market, and the dumbbell pieces are roughly 1, 1.75, 2.5,5, 15 kg, and the weight can be adjusted according to the training position.