King Tony 19-piece spline bit set, 1/4 inch drive, model 2021MR, covers sizes from 4mm to 13mm, designed to provide precise performance and strong grip on various nuts and bolts. It features high-quality manufacturing from durable steel with heat treatment to increase hardness and wear resistance, making it suitable for daily use in mechanical maintenance and automotive workshops. The set offers complete versatility for small sizes with high stability during work.