100mm dia rubber plunger with metal Lock Rod connector. Builds up pressure and forces through obstructions in drain pipes. Interlocking fittings enable rods to be rotated in either direction. Compatible with Silverline Lock Rod Drain Rod System (278373). 100mm dia rubber plunger with metal Lock Rod connector. Builds up pressure and forces through obstructions in drain pipes. Interlocking fittings enable rods to be rotated in either direction. Compatible with Silverline Lock Rod Drain Rod System (278373).