Home / PPE & Accessories / 50mm Single Worm Screw for Lockfast Rods50mm Single Worm Screw for Lockfast Rods Request a Quote Home / PPE & Accessories / 50mm Single Worm Screw for Lockfast Rods50mm Single Worm Screw for Lockfast Rods Request a Quote Single Worm Screws - work best when trying to clear a more solidified type of obstruction such as rags, fats, grease, silt or a severe root mass as these worms can be repeatedly wound into the obstruction like a cork screw to either break up the blockage and let it wash away or retrieve it for disposal.