There are four basic Thermostatic Shower Faucets designs: ball-style, cartridge, disc, and compression. Sometimes a faucet type can be determined by the outer appearance, but often the faucet must be taken apart to identify what kind of faucet it is. The four faucet designs come under two categories: washer and washer-less.The same basic principals apply to all Rain Shower Heads types when starting to take a faucet apart for repair or replacement.