There are the two marks(like this) on the two sides under the faucet-body. The blue mark indicates cold-water intake; the red mark indicates hot-water intake.
Keeping the white mark on the black plastic-ring with the mark 38 on metal cover in alignment. Holding the mark (of the thermostatic faucets handle) in alignment with the center of circular arc protuberant (the black plastic-ring); push the button of the handle down and keep the button in alignment with the mark (of the thermostatic faucets handle), and assembling the handle. Tightening the handle with bolt and then get the small cover on. Joint the water pipe with the 1/2 nut.

4.Assembling the parts of shower room thermostatic switch valve outside

Installing the metal cover (with shower symbols) on the switch valve above, adjusting the metal cover and tightening it with nut screw. Joint the water pipe with the 1/2 nut.

 The 38 mark is temperature safety-point. If need to above this safety-point, please push the button in the handle, and please to operating carefully in order to prevent scalding. For shower bath safety, the cold water will be reducing immediately within 5 seconds when you are adjusting the temperature from lower to higher. Please waiting moments to shower bath until the temperature is constantly. For your shower bath comfortable, the hot water will be reducing immediately within 5 seconds when you are adjusting the temperature from higher to lower. Please waiting moments to shower bath until the temperature is constantly... ..

Please not to shower bath when you just begin to adjust the water temperature, because the temperature is inconstant at this time. You would please to wait few moments and shower bath under the constant temperature..