<p>Hi Guys,</p>
<p>I am a bit puzzled by the sizing of the metal push on Leica lens caps e.g. A36, A39 etc. Can anyone help?</p>
<p>I have an A36 cap and the internal diameter measures 36mm as I expected. I also have what is purported to be an A39 cap but the internal diameter actually measures 42mm. Do the numbers refer to the internal diameter of the caps or something else?</p>