These compact fluorescent CFL helix spiral energy savers use an extra thin T2 sized tube, making them extra-compact.They make use of special technology to start faster and their smaller size means that they give off a more concentrated light; making them a much better replacement for traditional light bulbs than older energy savers. The ultra-white daylight version covers the full spectrum of natural daylight for craft work, graphic design, artwork or anyone needing a high quality light. Not suitable for dimming.Features a BC-B22d bayonet (22mm) cap base.Need more help in choosing a suitable light bulb? Read our guide Choosing Compact Fluorescent Lamps