Hi Gregor, we do not have specific instructions for this item.  It is used to unblock sink waste pipes/ washing machine or dishwasher discharge pipes that are normally 32 or 40mm diameter. The ‘pig tail 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 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?