This Crompton Lamps 4.2W LED candle light bulb with a BC-B22d bayonet (22mm) fitting is a direct replacement for a traditional 40W light bulb, but has the potential to reduce your home lighting bills and reduce the frequency of needing to replace your light bulbs.LED filament technology is much more energy efficient than traditional light bulb technologies such as incandescent bulbs. This not only helps you save on your energy bills but also helps the environment too.Whereas a traditional light bulb would use 40W to produce 470lm, this LED version uses just 4.2W equating to an energy-efficiency of 112lm/W.The beauty of LED filament light bulbs is truly enchanting, seamlessly blending vintage aesthetics with cutting-edge technology. The LED filaments within these bulbs mimic the classic look of incandescent bulbs, casting a glow that exudes nostalgia. Furthermore, LED filament bulbs extend beyond their aesthetic appeal by providing both energy-efficient operation and long-lasting durability, thus positioning them as a sustainable and environmentally friendly lighting choice.With a long life of 15000-hours, this LED candle light bulb boasts an incredible 8.2-year lifespan if used for 5-hours a day. These light bulbs dont need to be replaced as often which results in less money spent on replacement bulbs, and less time spent replacing them, too.Combine this superior longevity, negligible maintenance and replacement costs with the LED light bulbs notable energy efficiency then the savings gleaned from each light bulb has the potential to reduce your lighting costs by up to 90%.Cool white (4000K) bulbs produce a cooler, crisp light and are well suited to more stimulating environments. This makes them great in kitchens, workplaces and is also excellent for bathrooms as there is no colour cast; so applying makeup is much easier.Unlike older other energy-saving technologies, LED bulbs light up instantly, with no waiting time to warm up to full brightness.With a size of 35mm diameter with 91mm height, this LED candle light bulb will retrofit directly to any existing BC-B22d fixture; whether that be smaller domestic light fittings such as chandeliers or wall sconces or up to large-scale commercial installations.