All of our faucets are drilled from solid brass and contain copper waterways. We use two types of cartridges in our faucets: ceramic discs for single-handle faucets and 1/4 turn washerless discs for two-handle faucets. Ceramic discs slide over each other to open and shut the spout, which controls water flow and mixes temperatures inside the faucet body. They are high quality and do not need frequent repair, unlike a plastic disc cartridge. The only plastic part on the faucet is the sprayer which is made that way to be replaced if need be. Thank you.