D 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. D Lenovo ThinkVision S27-4e Monitor, 68.6 cm (27"), 1920 x 1080 pixels, Full HD, LED, 6 ms, Black Lenovo ThinkVision S27-4e Monitor. Display diagonal: 68.6 cm (27"), Display resolution: 1920 x 1080 pixels, HD type: Full HD, Display technology: LED, Response time: 6 ms, Native aspect ratio: 16:9, Viewing angle, horizontal: 178°, Viewing angle, vertical: 178°. VESA mounting. Product colour: Black