Milwaukee® HollowCore™ Magnetic nut drivers feature a thread-thru design for unlimited depth in threaded rod and long bolt applications. The magnetic universal driver heads fit 4X more fasteners including: square, hex, 12 point & spline. Designed for maximum durability the wrench ready hex steel shanks are forged and chrome plated. Milwaukee nut drivers are designed for the jobsite and include Milwaukee's Limited Lifetime Warranty.