1D Tight Radius Mandrel Bends. Ideal for Manifold Exhaust, Air intakes, Intercooler, Radiator Pipes. High Grade Stainless Steel Bends. Also used for the Dairy Industry Available is 90 Degree bends as 1D, the 45 degree bends are 1.5D. These are high quality bends ideal for building your own exhaust system, exhaust manifold, intercooler or air intake pipe. The tight radius bend allows you to get into the awkward angles. We stock a huge range of different sizes,so if you can not find what you’re looking for please get in touch.