I am sure you read this thread:
Selecting Your Cylinder Size
Remember to base it on the largest part of your penis. My base is the largest part, so that is what I measured to size my cylinder. For other guys midshaft or even glans might be the largest part.
—-
I bet if you need a 1.75" you could call them and ask them to substitute a 1.75" standard cylinder for the 2" cylinder in the pump master package. I would imagine they will have no problem with that.
From what I understand, the silicone sleeve is designed to fit 2" and above, but some say they have made it fit a 1.75"
On the otherhand I do not have a silicone sleeve and I find the standard cylinder to be quite comfortable.
At any rate, the best thing to do would be to call them and make sure you get the proper sized cylinder.