This main line snake is for cleaning out a 3″ or 4″ main line only. Do not use this snake in floor drains or pipes smaller than 3″. This snake has a 3/4″ thick, steel core cable with a cutter head. This gives it the ability to eat through tree roots and other tough debris. The 100′ snake is typically needed when the house sits on the circular portion of a culdesac in order to make the extra length to the center of the street.