I haven't used one yet, but I recall reading advice from others who have that the heat control is a good idea. One grower indicated that he/she had toasted some seedlings because temps got too high when ambient temps went up. At any rate, were I to use a heat mat, I would opt for one with a digital control. The key is that with the control, the temp will stay where you set it regardless of ambient temperature changes - like when a fan packs it in, or lights go out, etc. There are lots of options available on Amazon.