These professional sets of bolt and screw extractors are like nothing you have ever used. These Grabit screw extractors will quickly and safely remove all types of bolts and screws and as with all the Boa products, the ease of the use will surprise you. These sets will do exactly what you want, they fit screw sizes 4-24 and bolts 0.19 in. - 0.375 in. (5mm-10mm) and are efficient in time and performance. Great for: Engineering, Automotive, Marine, Agriculture equipment. 4 Piece set.