The SK Professional Tools DT Ratchets feature Double-Tooth technology designed to provide users with half the swing arc of a standard ratchet. These ratchets give the ability to retrofit the SK classic ratchet body with a Double-Tooth mechanism for an "upgraded" tool, the company says. The DT Series ratchets are currently available in 1/4" (120-teeth), with 3/8" (80-teeth) and 1/2" (100-teeth) drive sizes.