The standards
DIN 75490 defines the radio aperture in a car dashboard. A single DIN opening is roughly 180 mm wide by 50 mm tall. A double DIN opening keeps the width and doubles the height to about 100 mm. The aperture is the hole, not the unit: a unit's face can be larger than the aperture when the screen floats in front of the dash, which is how many modern large-screen units work.
What each allows
Single DIN dashboards were designed for a radio, not a screen. Options there are compact units, flip-out screens, or floating displays mounted proud of the dash — and in many cars, replacing a single DIN aperture with a screen means accepting a visibly aftermarket result. Double DIN is the natural home of the modern Android head unit: the catalogue's 6.86 and 7 inch universals are the compact double-DIN class, while 9, 10.1 and 13.3 inch units typically mount as floating screens over a double-DIN-sized opening.
Measure before you buy
Three checks take five minutes and prevent the most common return in the category. First, measure the aperture itself, not the trim around it — trim panels routinely overhang the standard opening. Second, check depth: large screens and their heat sinks need room behind the dash, and climate ducting often runs exactly there. Third, check what else lives in the aperture's neighbourhood — hazard switches, climate controls and vents that a floating screen would cover.
Where vehicle-specific units fit in
Modern dashboards increasingly ignore DIN entirely: the screen is integrated into sculpted trim, and no rectangle fits. That is the case the vehicle-specific range answers — a unit whose frame is the trim. If your car is recent and its dash is sculpted, start there rather than with DIN arithmetic; if it has a clean rectangular aperture, the universal range and this standard are all you need.