FOR SALE IS ONE (1) NEW TEN (10) PIECE HEX KEY SET METRIC (measured in millimeters (mm)) THIS SET OF TEN (10) HEX KEYS INCLUDES A CONVENIENT ROUND ALL METAL STORAGE RING AND THE MOST POPULAR METRIC (millimeters = mm) SIZES ON THE HANDY STORAGE RING. THESE ARE THE L SHAPE HEX KEYS, OFTEN KNOWN AS ALLEN WRENCHES. 1.5mm, 2mm, 2.5mm, 3mm, 4mm, 5mm, 5.5mm, 6mm, 8mm, 10mm ARE INCLUDED HER, A TOTAL OF TEN (10) SIZES. HIGH QUALITY CONSTRUCTION OF CARBON STEEL WITH BLACK OXIDE FINISH. SAE IS THE STANDARD OF INCHES, NOT METRIC. YOU WILL RECEIVE ONE (1) SET OF TEN (1) METRIC HEX KEYS ON STORAGE RING SHIPPED BY USPS FIRST CLASS MAIL. A hex key, also known as an Allen key or Allen wrench, is a small handheld tool that's used for for driving bolts and screws with a hexagonal socket. They are available in many different sizes, though they all have the same hexagonal-shaped tip. what is the difference between SAE and metric? (this listing is for METRIC type) The difference between Metric and SAE tools is similar to the difference between yards and meters. Metric fasteners, are (generally) used on imported, and SAE fasteners are (generally) used on domestic (USA) made. they are two completely different systems of measurement. BID AND BUY HERE IN IN ABSOLUTE CONFIDENCE SINCE I HAVE THOUSANDS OF POSITIVE FEEDBACK AND TEN+ YEARS EXPERIENCE. I SHIP WITHIN TWO DAYS OF RECEIPT OF PAYMENT, OFTEN THE NEXT DAY. $4.11 USPS FIRST CLASS GREEN SHIPPING USING RECYCLED PACKAGING MATERIALS AND ENVIRONMENTALLY FRIENDLY MATERIALS TO ANYWHERE USA. I DO NOT SHIP ANYWHERE ELSE. HAVE A GREAT DAY AND THANK YOU FOR STOPPING BY.......