The MILWAUKEE SHOCKWAVE Impact Duty 1/4 Drive 3 Extension provides better access in hard to reach places and offers extreme impact durability in high torque applications. The laser-etched size markings allow for fast identification of drive size and length. The dual-hole design and ring groove allow for easy attachment and removal of the extensions. All SHOCKWAVE Impact Duty Socket Extensions are backed by a Lifetime Guarantee and meet ASME industry standards.