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.Not suitable for dimming.Fitted with a SES-E14 small Edison screw (14mm) cap.Need more help in choosing a suitable light bulb? Read our guide Choosing Compact Fluorescent Lamps