I absolutely swear by the Microclimate Evo Connected 2, and have one on all 8 of my vivariums. They are easy to set up, have multiple options as well as low/high temperature alarms. Being able to control it from an app on your phone is extremely handy, and also means you're made aware of any alarms matter where you are. Honestly can't recommend it highly enough
Literally buy something every week, the staff are knowledgeable friendly and can't go any further with their awesome customer service and mass of stock availability at Literally unbeatable prices.