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 AOC U27B3CF/96, 27", 3840 x 2160 pixels, 4 ms, Black AOC U27B3CF/96. Display diagonal: 27", Display resolution: 3840 x 2160 pixels, Response time: 4 ms, Native aspect ratio: 16:9, Viewing angle, horizontal: 178°, Viewing angle, vertical: 178°. Built-in speaker(s). Built-in USB hub. VESA mounting, Height adjustment. Product color: Black https://www.gadgetspeak.com/review/AOC_27inch_U27B3CF-896918.html The screen surround is 61x36x1.5cm, the viewable screen is 59x33.5cm which gives the notional diagonal imperial measurement of 27inch es.Near the right edge of the base of the screen surround are five buttons which can give a huge range of settings depe...