Acute angle (air-bending) dies—used in air bending, these can actually be used to produce acute, 90 degree, and obtuse angles by varying how deeply the punch enters the die by adjusting the ram. Gooseneck (return-flanging) dies—The punch is designed to allow for clearance of already formed flanges Offset dies—a combination punch and die set that bends two angles in one stroke to produce a Z shape. Hemming dies—two-stage dies combining an acute angle die with a flattening tool.