Proto ratchet adapters, which are available in 3/8\u2033 (J5247), 1/2\u2033 (J5447), and 3/4\u2033 (J5647) sizes, are designed to fit onto the end of breaker bars to improve their versatility and also make it easier to access fasteners. ... Essentially, they turn non-ratcheting breaker bars and drive tools into ratcheting ones.
