Most chameleon keepers find that thermostats don't add much benefit, if any at all . I think you'll find that positioning a basking lamp to produce the correct temperatures at the basking location as measured by a combination of a remote digital temp meter and, if the budget allows, an infrared temp gun measuring the chameleon's skin temp will be all that is needed. Trying to use a thermostat to "regulate" the temperature has many pitfalls to it .