The bolt extractorós set is made of CrMo chromium molybdenum steel with a high hardness of 52-55 HRC

The sockets are designed to loosen baked-on bolts and nuts. They can also be used to loosen damaged bolts and nuts. The sockets can be used to unscrew bolts and nuts with right-hand threads.
Sockets for damaged, machined bolts, nuts in sizes 10, 11, 12, 13, 14, 15, 16, 17 and 19 mm have a special shape that allows them to wedge on a damaged bolt or nut, so that the damaged part is unscrewed.

The sockets work togetherwith a 3/8" ratchet, which allows more precise control of unscrewing force than with a 1/2"
ratchet
The unscrewed part should be knocked out of the socket with a special pin, included in the set. 
The product facilitates the work in professional mechanical and automotive service shops, allows to reduceóthe time of work and protects from damage other elements of the threaded connection