Snap-on impact sockets are heat treated to optimize impact service life with a lower hardness than hand sockets and are able to withstand repeated cycling loads of impact wrenches. Chrome sockets are heat treated to optimize non-impact torque application (too brittle for impact use and are not the safe choice). Snap-on® uses a proprietary blend of special alloy socket steel that provides long life and great strength. FLANK DRIVE® wrenching system delivers up to 20% more turning power without slipping or rounding while exceeding ANSI® performance standards.