This slotting tool makes a 20 mm x 6 mm slot in the side/s of 100 mm x 50 mm duct. This slotting tool is used in conjunction with slotting tool (Part No: TC1279-51) that makes a 42 mm x 6 mm slot in the base of 100 mm x 50 mm duct. This process is a simple mechanical means of preparing a shortened length of 100 mm x 50 mm duct for connection to another standard part. e.g. elbow, cross connector, etc.. Mating parts fit together using Joiner (Part No: TC1279-226). A standard mitre box ( Part No: TC1279-MITRE) is used on 100 mm x 50 mm duct, to ensure that a true 90 degree cut is achieved using a standard panel saw, with maximum 12 TPI.