Here is Snap on set
http://buy1.snapon.com/catalog/item.asp?P65=&tool=all&item_ID=647473&group_ID=675281&store=snapon-store&dir=catalog
Looks like there is also a 5/16" one also but not in this kit.
http://buy1.snapon.com/catalog/item.asp?P65=&tool=all&item_ID=634990&group_ID=675281&store=&dir=catalog