OTC's Glow Plug Remover Set allows you to safely and efficiently remove swollen glow plugs from many import and domestic diesel engines without damage Versatile set includes 10 mm and 12 mm split nuts, three spacers (3/16, 1/4, and 5/16 inch thick), plastic storage/organizer case, and instructions 10 mm split nut works on Ford 6.9L and 7.3L diesels, GM 5.7L, 6.2L, and 6.5L diesels, and various diesel engines in import vehicles 12 mm split nut works on various diesel engines in import vehicles, plus many agricultural and construction equipment diesel applications High-grade materials ensure quality performance over the lifetime of the tools