Polyester Wire Wound Sample Pack Heaters

Part # P08120A3:  0.4 watts per square inch; 120 volt; 8 inches x 12 inches 
UL Temperature Rating:  221 degress Fahrenheit (105 degress Celsius)
Relative Cost:  Polyester heaters are about 75% of the cost of a silicone rubber heater of the same size.
Waterproofing:  Moisture resistant,  the unit can be immersed for short periods (24 - 48 hours) without failing.  However, it is not designed for continuous immersion.
Applications:  Battery heating, animal heating, seeding beds

   
At this power density, these heaters take 4 - 5 minutes to reach a temperature that can be felt.  However, if insulated on one side, it can attain heating temperatures of as much as 150 degrees F.

This is the most common density for battery warming as there is little chance of overheating the battery case.   The limitation is watt density.

To See the Other Sample Pack Heaters:

Silicone Rubber Wire Wound Heaters
Silicone Rubber Etched Foil Heaters
Polyester Etched Foil heaters
Kapton Heaters
Mica Heaters