Originally posted by Philoslothical Rico, do you mean they extent outwards from the mount by 4mm? I haven't seen one like this. Mine, which I assume is a knockoff (it was priced as one) but has Pentax - m42 etched into it, it sits completely flush with the mount. I assumed that was normal?
Yes, that's normal. By flange width, I mean in diameter, not thickness.
With the narrow-flange infinity-focus clone adapters, those flange edges extend just a wee tiny bit (like 0.5mm) beyond the width of the bayonet blades, so the adapter fits snugly into the camera, flush with the mount.
With a wide-flange no-infinity-focus (NIF) adapter, the flange edges are out about 7mm beyond the bayonet flags; the thickness of that wide flange pushes the lens about 1mm away from the camera. That's why it's NIF.