Price is per foot. 4" is 6 watts per foot. It is recommended you keep your heat tape runs at a maximum length of under 30 feet for the 4" THG.
You manufacture this product yourself and will need to supply the wire and plug. The strips of heat tape are connected with two clips and two clip covers which are wired to a standard electrical wire.
You can also solder if your are comfortable with this. It is highly recommended that a rheostat, dimmer (use a dimmer intended for incandescent lights) or a proportional thermostat be used with this product.
Lengths of more than 40′ are not recommended. Due to how this element is manufactured the length can vary by +/- 1/4″ PER FOOT. Generally, it is less than that but ORDER EXTRA.
This heat tape MUST be used with a thermostat.
WARNING: Because this is a product that you manufacture yourself, there is no implied warranty and you incur all liability for it. Use common sense when using this or any other electrical heat element. This product is intended for indoor use.