Where can I buy a thermostat that allows me to set a maximum on how my tenant can set the heat?

I am a new landlord looking to find out where I can get a thermostat that will allow me to set how high the heat can be. I am not looking to freeze any one - I just dont want to pay for it to be 90 degrees in an apartment.Where can I buy a thermostat that allows me to set a maximum on how my tenant can set the heat?Check here:

http://www.amazon.com/gp/redirect.html?ie=UTF8%26amp;location=http%3A%2F%2Fwww.amazon.com%2Fgp%2Fsite-directory%2F%26amp;tag=funjok-20%26amp;linkCode=ur2%26amp;camp=1789%26amp;creative=9325

You will find what you like!

Good luck!