Home / Standards / GB/T 6139-2007 GB/T 6139-2007 Active Subland twist drills - Technical specifications 阶梯麻花钻 技术条件 Standard Type GBT ICS 25.100.30 CCS J41 Status 现行 Issue Date 2007-07-26 Implementation 2007-12-01 Responsible Dept 中国机械工业联合会 Drafting Unit N/A