DIN refers to a standardized radio/stereo size for vehicles (large enough to accept a CD). 1 DIN is the standard DIN specification. 2 DIN (or double DIN) refers to units that are twice as high as the standard DIN; half DIN is half high as 1 DIN. International standard ISO 7736 defines a standard size for car audio head units. The standard was originally established by the German standards body Deutsches Institut fur Normung, and is therefore commonly referred to as the "DIN car radio size". It was adopted as an international standard in 1984. Head units generally come in either single DIN (1 DIN), which is 50 mm high; or double DIN (2 DIN), which is 100 mm high. Please check the player position height of your car carefully. If 50mm, please choose 1 Din Car DVD Player / Monitor, and if 100mm, please choose 2 Din series..