Nibbler version for nibbler ASN 20. Pre-punched round holes can be easily and cost-effectively converted into square and rectangular holes. Particularly recommended for the production of rare dimensions (special shapes). Application: 1. Using a sheet metal punch and hand punch, pre-punch a guide hole with a diameter of 21.5 mm or with a diameter of 28.5 mm. 2. Insert nibbling tool with punch. 3. Use multiple punches (nibbling) to enlarge the round hole to the desired final size to form a rectangular or square hole. 4. To avoid diagonal punching, the final size should be marked out. Dimensions for ASN 20 with a-20.0 mm, b 9.0 mm, c 28.5 mm, pre-punching up to a diameter of 28.5 mm.