These are the drill head variants of the Renssi Set Screw Chain Knockers.
Renssi Set Screw Chain Knockers are made from durable carbon steel and are ideal for drain cleaning, root cutting, and descaling cast iron, clay, concrete, and PVC/ABS lines. The chains are adjustable, allowing you to increase or decrease the diameter of the chain by about 1".
Drill Head Set Screw Chain Knockers
The chain knockers are available for 5/16", 3/8", and 1/2" flex shaft cables with bare ends. They are not compatible with T-Slide flex shaft cables.