Allen key set is made of heat-treated chrome vanadium steel ensures durability and long service life. Black finish to prevent rust and against excessive stress and strain. Hex key wrenches are covered in anti-rust oil to prevent getting rusty, please wipe off the excess oil before using. Allen wrench set covers almost every common size you used for work and DIY projects around the house:15 pcs short arm wrenches (0.7-10mm); 15 pcs long arm hex key wrenches(0.028-3/8 inch); 2pcs additional extension bars(5mm-6mm / 8mm-10mm). Precision machined and chamfered edges provide a comfortable fit and smooth insert fasteners, and protect your hardware from wear. Classic-shaped design and additional extension bars make extra reach and more torque. Kept tidy and organized in a sturdy carrying case with size indexed individual slot for each wrench for quick size selection and easy organizing. FASTPRO 32-Piece Hex Key Set, Green