Sturdy Construction: Crafted from premium high carbon steel with 2.5mm thickened wall for impacts resistance, ensuring without bending or deformation during installation double Size Versatility: Features M13 / M14 double head sockets for wide compatibility with various bolts and nut in construction and home projects Protections: High temperature electrophoretic surfaces enhances rust resistance, maintaining long lasting in humid environments Effortless operations: Hollow design allows easy insertion of screwdrivers for added torques, while the extended 496mm length provides better reach in tight spaces accuracy Installation: Fully hollow socket slides smoothly onto threaded rods, offering perfect alignment for ceiling joists nut and expansion bolt fixing, Manufacturer: TFAOYS