The Cal-Van Tools 6-pc Diesel Injector Line Socket Set, No. 39660CV, is designed to loosen and tighten injector line fasteners found on most diesel engines. The flexible head allows 90-degree access and the 6PT crowsfoot head applies a secure grip without damaging the fuel line fastener. Featuring a robust, chrome-moly construction and corrosion-resistant finish. The 12mm and 14mm flex head sockets come with a 3/8" drive; while the 16mm, 17mm, 18mm, and 19mm flex head sockets come with a 1/2" drive.