This 0.5-3mm twist drill chuck set is made of copper with excellent workmanship.The collets can go with twist drill as a mini hand drll for ABS board, aluminium shet, paperboard drilling. Specifications: Material: copper Drill Collet Size: 0.5mm, 1.0mm, 1.5mm, 2.5mm, 3.0mm Feature: Excellent workmanship 0.5-3.0mm drill collet Go with twist drill as a mini hand drll for ABS board, aluminum sheet, paperboard drilling