I have a couple different size Rena Heaters in a few tanks.I like them because they are pretty simple to work with. The glass tube is pretty thick and has held up without a crack the few times that I bumped it against the glass. The suction cups that hold it against the tank work well and keep it exactly where I place it.And the setting of the tank temps is clear and from what I've witnessed,been very close to what the thermometer in the tank was reading.
Overall,I've been very happy with the Rena Heaters.

Pros: heater has been dependable

Cons: none

Rena heaters are very reliable and work great

Pros: Discreet and works great

Cons: none