F means that the product is rated in its category in terms of energy efficiency. The Energy Labeling system is based on EU Regulation 2017/1369/EU. F DECT 500 International, Smart bulb, Silver, White, LED, E27, Multi, 2700 K DECT 500 International. Type: Smart bulb, Product colour: Silver, White, Bulb type: LED. Energy efficiency class: F, Energy consumption per 1000 hours: 10 kWh, Energy efficiency scale: A to G. Width: 62 mm, Depth: 62 mm, Height: 118 mm. Quantity per pack: 1 pc(s). Operating temperature (T-T): 0 - 40 °C