Actually two clicks would be 500 iu on one ml slon pin. So one click on one ml slin pin is roughly 250. That's why I wanted to dilute it
I transferred the contents of my last pen and have been using it so I can't give an accurate measurement on the amount of solution that comes with the pen. I do believe it is much more than .5cc. If someone has a full pen and will measure the contents I believe we can come up with an accurate method.
I do know 1 click will yield barely enough solution to create just a bubble. 2 clicks doesn't produce much more. Definitely not anything close to 250 for 1 or 500 for 2. Try it. Pull the plunger out of a slin pin and turn 1 click on the pen, then deposit the results of 1 click into the slin. Better get a magnifying glass, you'll need it!