The 13mm Bypass Wrench, No. BY13, from Assenmacher Specialty Tools is designed to assist in removing and replacing hard-to-reach Detroit Diesel Turbo bolts and nuts by going around obstructions that would typically be in the way. It is also ideal for other applications requiring a 13mm wrench. The BY13 is made from forged steel and has a 3/8" drive. The tool is also available in 10mm (No. BY10) and 14mm (No. BY14) sizes.