Glass bulbs look just like classic incandescent bulbs. They are suitable for decorative open lamps and especially for crystal chandeliers. LED filaments emit light evenly in all directions. Unlike conventional LED chips are encapsulated in a transparent synthetic sapphire and coated with phosphor. It is very thin with a diameter of only 1.2 mm and length of 45 mm. Sapphire has a much higher thermal conductivity than glass. This ensures better cooling of the chips and thus a much better parameters, than cheaper glass encapsulation. This is COG technology which allows to achieve the more than 100 lumens per Watt and excellent color rendering index Ra ≥ 80.