Tubes are strong and durable --Gently used This set includes six interchangeable tempered steel tubes and forged steel handle. Sizes 4.8mm, 5.2mm, 5.6mm, 6.4mm, 6.8mm, 8.mm. I purchased this from Tandy Leather 19.99 it is also sold on WalMart.com 19.99. I used this several times, but like new condition. Works well and makes clean holes.