When spinwelding our polyethylene fittings in a tank, you need to carefully cut a hole in the tank to receive the fitting.  Spinweld fittings are self-centering, but the hole size must be precise in order to keep the fitting from getting out of alignment while it is spinning very fast and melting the plastic.  For your convenience, we offer the sizes of hole saws needed to weld all the fittings we sell. 

The saws have bi-metal construction with high speed steel teeth, so they can saw through plastic, drywall, wood, plywood and metal. 

Don't forget to buy the correct size arbors to go with the saw sizes you buy, so you can mount the saw in your drill chuck.