Looking at the pdf of the "original line catalog', SR, just means "stainless rod". Because stainless steel is significantly weaker (tensile strength) than carbon steel, I would think that such a cylinder might be more appropriate for a food plant with daily wash-down than for a robot. I just recommend the original line, unless you need a magnet or a cushion, which also work very well.
The link for the 'original line catalog'--which is like a paper catalog but has all your info is:
https://www.bimba.com/Global/Library...iginalLine.pdf
As for CAD, you don't need to draw these, Bimba gives away great models for free once you've built the part number (sometimes a guess) using the catalog link above.
You'll need to enter some criteria in the blanks here, and then go to 'download' above the picture to tell it what type of file you need. I've mostly used them in Inventor, but they worked great.
http://www.bimba.com/Products-and-Ca...Line-Cylinder/
Also, I know that the math is easy and you probably want to do it yourself, but if you want to just 'read' how much force each size bimba can generate at our pressure (60psi), I made this handy chart.
https://docs.google.com/spreadsheets...Kgm5OY19c/edit
Best of luck.