Faucet Handles
The part you see most often is the faucet handle. This part is made of metal on most single-handle bathroom, shower and kitchen faucets. However, there are some plastic Moen faucet handles. On double-handle bathroom faucets with round knobs, the handles are plastic. These decorative handles are easy to spot because they are clear and have a decorative cut. Some tub and shower combination faucets have similar handles made of plastic which are much larger. Handles also have caps and plugs covering up the handle screw, which are plastic.
Trim Pieces
The Moen shower faucet has a trim piece fitting around the base of the faucet. This piece is chrome plated or brushed nickel. The piece is made of metal and designed to take wear. As a baseplate for the entire faucet, it is integral in the look of your faucet. It also prevents water from splashing into the shower walls. Typically, this part is secured by metal screws mounting it right to the shower valve fitted to your home's plumbing.
Shower Valves
The Moen shower valves are always made of metal since they withstand lots of pressure from your plumbing. These parts are made of hard steel and designed to fit other brass or copper pipe fittings. The parts are molded and welded together to form a completely watertight valve system. If you install one of these shower valves, you will notice it is heavy and durable. It solders onto the pipe fittings that connect directly to your home's water pipes.
Internal Parts
Moen shower faucets also have stop tube kits made of metal, which slide over the cartridge -- the disc valve that fits into the shower valve. The cartridge is made partially of plastic and partially of ceramic. The discs inside of the cartridge are pure ceramic because they are shaped to be perfectly flat and therefore watertight. In Moen disc faucets, there are seals under the cartridge made of rubber, which enhances their watertight capabilities.
Bases and Spouts
Moen faucet bases and spouts are made of metal. The base of bathroom and kitchen faucets must be very strong and durable to absorb the constant use and operation of the handle. The base also helps maintain the integrity of the faucet. Spouts are usually made of thin sheet metal coated with a chrome surface to add shine and luster. This solid construction reduces the chance of cracking and gouging, which is a concern with plastic.