This is the ebay item number:350661302052, I use the 1kw version (£42), it has a built in thermostat, max output 32 degrees. I switch it on around 5pm and leave till morning, no idea how long it tanks to heat the 350l flat tank but I doubt it's on all night. The heat wrap is listed on Amazon as: "Foil Survival Emergency Blanket", I leave this on all day. The heater sits on the bottom of the tank, it appears to heat the whole tank to 32 degrees without any cold spots. Not measured temp at brush, it's not "hot" but pleasantly warm, certainly would not crack glass. Main aim was to keep the hoses pliable which it does admirably, it also keeps the van defrosted (no need for my greenhouse heater).