Quick Release Dimensions

I’m trying to understand quick releases for a project I’m working on. When they talk about the dimensions of a quick release, they say things like 5 x 16-42mm. Does anyone know what the numbers refer to? Is it 16 mm inner length when closed and up to 42 mm inner length when open (by the way, these are the dimensions of a seatpost QR, in case these numbers seem very small for front or rear wheels)? I’ve also seen ones that just give one number (e.g. 28.6 mm. Are they talking about the width they fit, or are they talking total length? And is that the minimum width they fit or the maximum? I’ve looked around the internet, but it seems like they assume you already know what it means if you’re going to be buying one.

In case anyone’s interested (and judging by the responses, not many people are), I’ve come up with the dimensions of a seatpost Quick Release. I haven’t found this information anywhere else on the Internet, so this might come in handy for someone else someday.

I’m actually quite interested in this, but can’t really help you straight away. I think when a QR is quoted as a single number its usually the frame-tube diameter, but the other notation (5x16-42mm) I’ve never seen before…