Tubes are strong and durable. Sizes 0 through 5: 5/64" (2.0 mm), 3/32" (2.3 mm), 1/8" (3.1 mm), 9/64" (3.5 mm), 5/32" (4.0 mm) and 3/16" (4.8 mm). Each set includes six interchangeable tempered steel tubes and forged steel handle. Use wood or plastic cutting board as a base to punch into. This will help protect your tools and your table top.