The Snap-On Socket Extension Bars set includes four bars in 3/8″ and 1/4″ sizes, designed for precise and efficient tightening and loosening of nuts and bolts. Manufactured by Snap-on, a trusted brand in the industry, these high-quality extension bars are essential for mechanics and DIY enthusiasts alike. The set is perfect for reaching tight spaces and accessing nuts and bolts with ease, making it a valuable addition to any toolbox.