New towel radiator

During our renovation work we have fitted wet UFH to all our bathrooms. We are at the stage where we can still fit towel radiators for additional heat but this will have to be electric.

I am unfamiliar as to how these work. Are they simple on/off switches or is there a fixed (or wireless thermostat which enables you to put them on a timer? Also are they oil or water filled rads and do they need any maintenance e.g. topping up or safety checking?

Any switch needs to be outside the bathroom ( or a pull switch). The outside switch could be a time switch. I think the thermostat is internal to prevent overheating, no room temperature control as such.

I have 3 of these always on the low setting, very good.
There are different types of t/stats I have 1 that is infinitely variable , the other 2 are pre-set with 4 options, I prefer these as there is an LED showing the level that is set.

Could you both pls send some links on Amazon or whatever for me to get an idea of what you are referring to?

Are these oil or water filled? Maintenance?