MOST-COMMONLY USED SIZE: - This 6-piece hex shank drill bit socket adapter set package includes 3 most commonly-used bit sizes: 1/4"(x2 pcs), 3/8"(x2 pcs), and 1/2"(x2 pcs); Length varies from 50mm to 73mm.With multiple choices, you can pick the most appropriate one to use. WIDE APPLICATION: - Each impact driver socket adapter bit has a universal 1/4" hex shank for all quick-change drill chucks. Fits snugly and securely in your drill chuck or hand-held driver; an ideal tool set for both professionals and DIY lovers; DURABILITY: - This 6 PCS impact grade socket adapter set is made of industrial grade chrome vanadium steel (Cr-V) with extra black Phosphate Coating Treatment for higher hardness, wear resistance and corrosion resistance. Heavy-duty material ensures long service life HELPFUL TOOL SET: -This 6 pcs impact bit socket adapter is an ideal tool for car repair, DIY and most general home repairs. TIGHT LOCK: - The spring ball bearings on each square head are securely locked in the socket to avoid slipping during use. Easy to install and remove;