An oblique sketch is based on an enclosing box whose principal axes are drawn at specific orientations. Oblique principal axes are unlike the isometric axes in that 2 of them are at right angles while the third is at any convenient angle. An oblique shows the front face without distortion, in its true shape, and this is its prime advantage. The oblique sketch is useful for objects that are primarily cylindrical or that have many circles or curves in one plane or a series of parallel lines.