I just want to add that my cylinder has lines every 1/2 inch so I know what my ideal length is. So in addition to pumping at a desired vacuum, somewhere under 5, I visually know where to stop my initial pumping and watch it grow on its own to my maximum pumped length. It then usually recedes slightly as the vacuum is slightly reduced in reaction to the volume increase of my penis. I than pump back up to my max line or return to the desired vacuum level. The two desired max levels (HG or length) act as a double safety check. Over time the desired pumped line will hopefully need to be adjusted.
If your cylinder is not marked with lines, you can use adhesive/painters tape to mark your place. It is also a good idea to maintain your initial tape mark to refer to later when your latest max line is further out on the tube.
If your cylinder is not marked with lines, you can use adhesive/painters tape to mark your place. It is also a good idea to maintain your initial tape mark to refer to later when your latest max line is further out on the tube.

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