The MILWAUKEE® 4” Standard Chain Knocker for the M18 FUEL™ High Speed Chain Snake delivers a wall-to-wall clean that can tackle grease and soft blockages. The standard chain knockers are best used in PVC, clay, or fragile pipes. These steel chain knockers feature durable construction to tackle tough clogs in 4” lines. Featuring stainless steel set screws for corrosion resistance. Additional accessories available for more efficient descaling and breaking up grease: 1-1/2” Carbide (48-53-3024), 2” Carbide (48-53-3025), 3” Carbide (48-53-3026), 4” Carbide (48-53-3027), Grease Penetrating Head (48-53-3028).