Years ago, instrument manufacturers adopted the DIN standard for panel mounted instruments, with standardized panel cutout dimensions for controllers, recorders, and other boxed mechanical devices.
And while the cut-outs are a standard size, the area occupied by the instrument’s bezel, its footprint, is not. Some bezels extend quite far beyond the cut-out, others barely extend beyond the cutout.
So, you need to pay attention to both the cutout and bezel specs when you’re planning a first-time install or a replacement upgrade. A designer who lays out a panel needs to be aware of how close one panel mounted instrument can be to another.
The chart below shows the sizes, which are verbally referred to by their fractional titles, like “quarter DIN” or “eighth DIN”.
The rectangular size, 1/8 DIN, is common in both vertical or horizontal installations, the 1/32 DIN size is most commonly found as a horizontal panel cutout.
By the way, the acronym DIN stands for “Deutsches Institut für Normung”, or “German Institute for Standardization”. (Doesn’t change anything, but I thought you might like to know where it came from.)