Unique X-Beam design allows you to apply force to the flat of the wrench which reduces hand fatigue and increases surface contact by over 500%. Up to 25% longer beam to access those hard to reach fasteners. Surface Drive Plus provides stronger grip on fasteners and delivers up to 25% more torque. Surface Drive on ratcheting box end improves box end strength and reduces fastener rounding. First tool recognized by the Arthritis Institute to significantly reduce the risk of carpal tunnel This 12 piece Metric X-Beam Ratcheting Combination Wrench Set. Includes: 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, 16mm, 17mm, 18mm and 19mm. .