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 Dahua Technology DHI-LM27-E331A, 68.6 cm (27"), 2560 x 1440 pixels, Quad HD, LED, 5 ms, Black Dahua Technology DHI-LM27-E331A. Display diagonal: 68.6 cm (27"), Display resolution: 2560 x 1440 pixels, HD type: Quad HD, Display technology: LED, Response time: 5 ms, Native aspect ratio: 16:9, Viewing angle, horizontal: 178°, Viewing angle, vertical: 178°. VESA mounting, Height adjustment. Product colour: Black