There are two types of kitchen faucet connections: threaded and slip-on. Threaded connections have a male fitting that screws into a female housing, while slip-on connections have a male housing that slides over a female fitting. The most common size for both types of connections is 1/2 inch. However, some newer models may have 3/8 inch or even 1/4 inch connections. It is important to check the size of your kitchen faucet connection before purchasing a new faucet, as not all models will fit all sizes of connections.