If you purchase one of the acrylic pumping cylinders and do not have this male connector to fit into the tube coming from your hand or electric vacuum pump, you will need it. This connector fits into the tubing and clicks into the female connector on the top of the cylinder to allow air to flow free as you place vacuum into the cylinder.  When up push in on the one-way valve release mechanism and release this connector, the vacuum will stay inside the cylinder until you place this back into the valve or unscrew the threaded female valve on the acrylic cylinder.  Either way works.

This is a special connector size and specific diameter. They can only be purchased from one retailer that we know of and are expensve to get.  We found out that other connectors while they look the same will not work.  This barbed connector fit snugly into 1/4" ID tubing.

Let us know if you have any questions about this connector or the vacuum pump you have.