The Powerbuilt 28 Piece Zeon socket set combines the most commonly used SAE and metric socket sizes. Each socket features the patented Zeon design. Powerbuilt Zeon sockets are designed to grip and turn damaged and rounded nuts and bolts. The patented design will grip and turn hex heads up to 85% rounded. And they work just as well on new nuts and bolts. The secret is the patented Zeon socket design - the more you turn them the harder they grab and hold damaged hex heads. Zeon sockets are heat-treated to hardness HRC 38-56 for maximum strength and durability. And you'll drive the sockets with strength and precision using the included 90 tooth Powerbuilt XT90 ratchet. This sealed head professional grade ratchet is the most durable ratchet in the Powerbuilt line. It requires just a 4-degree swing to engage the ratchet, making it ideal for the tightest spaces in the engine bay.