I only picked out the shown Thermostatic Shower Valve due to good customer reviews, but you will have to browse through all options for the specific needs of your shower through the following link:
Browse all Thermostatic Shower Valve accessories here.
The thermostatic shower valve shown here is the Kohler brand valve. You can adjust the settings to get a comfortable temperature zone every time you shower.
Read more about them, or buy them here.
This source has almost every possible version of thermostatic shower valve for your specific plumbing needs. The exact one shown here is from a well known brand and has some decent customer reviews that you can read for yourself through the links on this page.
Some of these valves may only ship in the U.S., and some will ship internationally. You will have to read product details carefully before ordering.
This one is the Danze two handle half inch thermostatic shower valve. It also has a ceramic disc volume control. So this one controls both volume of water flow as well as the water temperature. It can handle and provide 8 gallons of water per minute as a pressure of 45 PSI. All required mounting brackets are included. Read more about this one, or browse through a bunch of other similar options by clicking the image of this dual handle shower valve seen here. You will also find a bunch of customer ratings and customer feedback comments.
Along with just about any type of valve you may need, this source also provides trim and other accessories as well. One example of available trim is this chrome version shown here. You can get this polished chrome version, or the same trim in a color called brushed nickel. This is just one example of many to give you a rough idea of what this source provides. See more details about this one shown, or browse through a massive selection of others by clicking this picture.