Depends on how cold your room (or house) gets year-round (like in winter, or even summer if you use a lot of air conditioning). So you may need both, but I
cannot answer that for your house or the climate wherever you are. It's always better to have both connected & ready to use, you can just leave one off or on
low, but when it gets to be cold in the winter, your snake could get sick if he gets too cold before you notice or can get to the store. Just be sure he has a cool
side to the cage too, for safety & for your snake to choose what's needed ("thermo-regulate").

Thermostat: start a new thread (or search existing ones here) to get input from others...I haven't bought one in quite a while & things change...ok?