BettaTherm - Betta Bowl Heater - any experience?

[Newtonbetta]

I have a 1.5 gallon bowl, filtered.

Does anyone have experience with this heater? My main concern, of course, is overheating. The betta is kept in an office so no one is there on the weekends.

Any one know about these small 7.5w heaters, or could suggest an alternate? Price is not an issue, but space is (hence the small tank).

[chargers505]

I will be buying the same heater for my girlfriend's betta tank. I looked at it at my local pet shop the other day. I guess there's no preset dialer. It'll raise the temperature 5-10 degrees above room temperature so I doubt it'll be able to overheat.