Dear Simon

It is used to unblock sink waste pipes/ washing machines or dishwasher discharge pipes that are normally 32 or 40mm in diameter. The ‘pigtail end’ is unlikely to go down through the sink plug hole, therefore you will either have to undo one of the joints on the P trap/ U bend or insert it down the exposed discharge pipe. The wire can then be used in a ‘push/ pull action to free the blockage or on longer runs, you can rotate the handle to rotate the head. I trust that this helps.