This is a rare set of 1/2" drive Snap-on S/O overstrike 6-point knurled sockets in three sizes: 5/8", 3/4", and 7/8".  These were made in early 1920's and are over 100 years old.  Made in the United States, these tools are highly collectible and sought after by mechanics and tool enthusiasts. The knurled design provides a better grip, making it easier to use in tight spaces. This set is a must-have for any serious mechanic or tool collector.