For performing thread repair in confined and difficult to access areas where a traditional T-handle cannot be used. Manufactured by US.PRO Tools (formerly known as Bergen Tools), one of the more respected hand tool manufacturers on the market. Forged from Chrome Vanadium Steel (CR-V) for longevity and durability and helps resist abrasion, oxidation and corrosion. The sockets are designed to accept square shank, thread cutting taps which are held in place by a strong internal magnet. Smaller tap sizes have a 1/4" drive socket, and the larger have a 3/8" drive. Both can be used with extension bars and operated by a hand ratchet. • For tap sizes from M1.5 to M14 • Precise apertures to match square shanked taps • Powerful internal magnet to retain the tap • Ideal for difficult to access areas • CR-V Sizes: 1/4" Drive sockets: 2.8, 3.4, 4.0, 4.