A polymer lid for capping the mouth of a PET bottle having a neck with a male thread, the lid comprising a threaded female cylindrical section for engaging the male thread of the neck; an outer surface comprising an arcuate skirt consisting of at least three quarters (270°) of a torroidal cylindrical section around the female cylindrical section; and further consisting of a protrusion having first and second surfaces than meet at an apex whose maximum extension protrudes between 1 mm and 5 mm from the inner cylindrical female surface; the protrusion for engagement by a thumb of a person attempting to open the bottle, enabling increased torque in a counter-clockwise direction for removal of the lid from a PET bottle.