I purchased two of these such that I could fill my hydration pack with my filter without taking the hydration pack from my bag. I spliced one into the hydration pack hose and the other into the line from my water filter. Works like a charm. Apparently I didn't read well enough when purchasing and didn't realize they had a built in shut-off valve such that when disconnected, water will not flow through the female end. It saved me from using a separate shut-off valve on my hydration pack that I was planning to install. The up side is that water won't flow, but the down side is that sometimes you want it to and you have no choice then but to insert the male portion to get the water flowing.