cables - 5-pin DIN socket advertised as MIDI, not the same as on my MIDI gear

I bought a 180-degree 5-pin DIN chassis-mount socket dirt-cheap for a project, but I saw that it looks quite different from the MIDI outs on my MIDI gear; I did some research but couldn't find any info on MIDI plugs being any kind of specialized DIN shape, just 5-pin 180-degree DIN.
I just ordered another chassis-mount socket from UK, advertised on their site specifically as being for MIDI, but it's the same as the cheap one I got before, and doesn't appear to be the same as on my gear. I currently don't own a cable, so my own tests are pending. But when they say MIDI is 180-degree 5-pin DIN, is it really exactly the same or is there some other specification that needs to be made between different layouts of 180-degree 5-pin DIN? Diameter of the semicircle? Size and shape of the aligning nub?
I can easily believe no one has ever actually ordered this product and tried to use it since the UK online store has been running! What I can't believe is that this information doesn't exist anywhere within Google's reach. It's out there somewhere.