Kikuwa 210mm Carbon Steel Professional Japanese Bonsai Knob Cutter Standard Knob Cutter - 210mm - Carbon Steel FEATURES ~ Long Handles For Ease Of Use ~ Sharp Blades For Precision Cuts ~ Strong S55C Carbon Steel For Durability ~ World Trusted Bonsai Tool Manufacturer Knob Cutters are a pretty simple tool. Sometimes in bonsai when we make a cut to a trunk we can often times get a knuckle where it heals if you cut flush with the trunk, On trees with thicker callus as it heals it creates a bump and this can look unsightly. To prevent this from happening we have Knob Cutters. Basically after you have made your cut with your branch cutters you can then go in with the knob and create a concave cut ( cutting just past flush ). what this does is allow the the tree to heal flush by allowing the callus to fill in the concave cut we made. Knob Cutters are also a great tool for working down larger cuts, wounds or stubs on bonsai trees. the sharp blades make this job easy and the concave design allows you to remove larger amounts of wood. It's worth noting that S55C steel can be prone to rusting if it is not properly maintained, so it is important to keep it dry and clean, and to oil it regularly. You can purchase Camellia Oil Here