If the chain knocker offers an option for chain thickness, typically you'll find two choices: 3.5mm and 4.0mm. This defines the thickness of the chain links in that particular chain knocker. Choosing the correct chain thickness for your chain knocker depends on the specific requirements of the job you're facing. 3.5mm Chain Thickness: Ideal for maximizing flexibility, these chains require less torque, making them suitable for use with smaller power sources. They navigate bends more smoothly, enhancing overall manoeuvrability. This option is recommended when seeking ease for your drill and the highest level of flexibility. However, the flexibility is also influenced by the shaft's rigidity; for tight bends, consider a thinner shaft combined with 3.5mm chains for optimal results. These chains are by weight the lightest option available. 4.0mm Chain Thickness: Offers increased efficiency and speed, suitable for straight lines or paths with few, easy bends. These chains demand more torque but excel in power and cleaning efficiency in less complex piping. We recommend using 4,0mm Chains only with 10mm (⅜″) or 12mm (½″) flex shafts since they are more rigid. In summary, 3.5mm chains are your go-to for intricate, bend-heavy plumbing systems requiring gentle handling, while 4.0mm chains are best for more straightforward, less complex systems where speed and efficiency are priorities. Always consider the combined effect of chain thickness and shaft flexibility on the manoeuvrability and efficiency of your cleaning tasks.