Some items are worth buying on eBay just for one part. In this case an aquarium heater comes with a neat 100W spiral heating element inside it. Or, as mentioned in the video, the whole heater could be mounted through the side of an enclosed tank with a suitable sealing gland to act as a low power heating element with a rugged glass body. The wattages available are typically 50, 100, 200 and 300W with the main difference being the length of the heater section.
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