Can be used on SAE or metric fasteners. Low profile design helps gain access to fasteners in tight spaces. Proto® Bolt Extractor Sockets can be used in combination with other drive tools (such as extensions, universal joints or ratchets with short arc swings) to help reach fasteners in difficult locations. Proto® Bolt Extractor Sockets make it easy to remove rusted, rounded or damaged nuts and bolts. Sets provided in mar-resistant tool holders. The non-working hex-shaped end can be turned with wrenches or sockets. The working end has 18 – 30 teeth in a hexagonal configuration to help grip rounded hexagonal fasteners, round head bolts and pan head screws. Through-hole design helps gain access to fasteners at the end of long bolts or studs.