The RIDGID K9-102 2" (64298) FlexShaft 2-Chain Knocker is designed for use with the K9-102 FlexShaft Drain Cleaning Machine and provides wall-to-wall cleaning in 2 in. pipes. The chain knocker expands to a pipe's inside diameter to break up blockages. The model 64298 Chain Knocker fits 1/4 in. cable and is equipped with two chains. The chain knocker is ideal for all pipe types, including for soft blockages and grease.