AOC Monitor 28" 4K UHD x Res Free-sync 1ms cd/m2 Brightness VGA DVI-D HDMI (MHL) DisplayPort UVF. With up to 4K Ultra HD. Best Buy has honest and unbiased customer reviews for AOC - Featured 28" LED 4K UHD FreeSync Monitor - Black & silver. Read helpful reviews from our. UVF LED backlight © AOC. Please check with the local dealer or AOC branch office for confirmation. CD Manual. Warranty card.