Thank you for choosing Danco products. Some stems, such as Danco #09330 (3H-10H/C)  #10472 (4Z-24H/C) ‎ are reversible. Just click on this link https://www.danco.com/support/installation/ and input the model # into the search field to find their reversal guides. Other stems simply turn around in the faucet body to change direction. In some cases, there are separate stems for the hot and cold side, and you’ll need to get the correct stem.