The classic Louis Poulsen PH 5 Pendant Light was developed by Poul Henningsen in 1958 in response to constant changes to the shape and size of incandescent bulbs by bulb manufacturers. Irrespective of how the light is installed or the light source used, the PH 5 is and remains completely glare-free. The fixture was christened PH 5 due to the 50cm diameter of the main shade. Poul Henningsen wanted to improve the colour reproduction characteristics of the light source in the PH 5. Small red and blue shades were therefore inserted to supplement the colour in the part of the spectrum where the eye is least sensitive.