RIDGID offers a wide variety of FlexShaft® drain cleaning accessories in different sizes for the most cleaning efficiency on the jobsite. Depending on pipe size, pipe material and blockage, there are different chain Knockers and Brushes for every job. Knowing when to choose Brushes or standard, carbide tipped or penetrating head chain Knockers can help you get the best performance out of your machine. Chain Knockers With Carbide Tip - Chain Knockers with carbide tips clean wall to wall and are ideal for removing scale and light roots as well other grease and soft blockages in hard walled pipe types. Penetrating Chain Knockers With Carbide Tip - Penetrating head chain knockers with carbide tips can be used to open full blockages such as grease, hair, and other soft blockages.