Generally speaking, the 20 kg dumbbells in the store refer to a pair weighing 20 kg, that is, the single weight 10 kg, and the ones in the store are generally not heavy enough. You'd better ask if they are standard weight or full weight.

If conditions permit, you must buy electroplated ones. Plastic packaging stinks. As for how much to buy, it depends on your strength. It's best to buy a detachable one with a large weight, so that even if it can't be used now, it will be used later.

At present, the electroplated dumbbells on the market are 8- 10 yuan per kilogram.