A set of Metric Matco Tools Impact sockets, 1/2 inch drive, 6 point.  Included ar 10mm thru 22mm, the 24mm, and the 27mm.  The 20mm socket has a different part number from the rest of the set,  

The part numbers are as follows:  

CP10M6, CP11M6, CP12M6, CP13M6, CP14M6, CP15M6, CP16M6, CP17M6, CP18M6, CP19M6, CP20M6A, CP21M6, CP22M6, CP24M6, CP27M6