The PH 3½-2½ lamp was designed in 1928 to direct most of the light downward, based on the principle of the three-shade system created by Poul Henningsen. The lamp was crafted from the original drawings by Poul Henningsen and featured a first-edition lampshade bracket with adjustable screws.

The top layer of the lampshade has curled edges, which serve both decorative and stabilizing purposes, making it appear thicker than the actual material. The two lower layers are made of hand-blown opal glass.

The light source is hidden from view at any angle, and each layer of the lampshade evenly diffuses the light, softening the brightness and reflecting it downward while creating a gentle, ambient glow.