Double Worm Screws - work best when the blockage is perhaps of a larger or looser nature as the twin prongs can be wound into the obstruction until they grip hold which enables the blockage of perhaps rags or roots to be withdrawn and disposed of.
MIS (Submitted on 16th Feb 2018)
these work very very well on roots such as willow. i did manage to bend the arms digging out a rock from a 9" drain. bent the arm back again and works well