The new valve core must be replaced with your faucet.
First find out if your faucet is single or double,
Is it a single cold water faucet or a hot and cold water faucet,
It is also necessary to know the size of the valve core of your faucet. The size of the valve core also refers to the size of the water flow. Small valve cores are generally not easy to buy in the market, so generally remove the old ones and ask the seller to replace them.