Product DescriptionThis set is designed for the removal of bolt heads that have rounded off or have become rusty or painted over. They have a unique reverse spiral flute design that latched on to the top of the bolt head and removes them, works with nuts to. This set can be used with a 3/8" ratchet or with a spanner/adjustable wrench. Sizes - 9MM(3/8"), 11MM(7/16"), 13MM(1/2"), 14MM(9/16") & 15MM(5/8"). Supplied with a carry case.Questions And Answers