Source Outdoors Magnetic Clip (Black)
Magnetized Tube Clip-  – 2”L x 1.2” W x 1”D Packaged .Weight: .088 lbs. Magnetized drink tube keeper holds hydration hoses securely in place. Modular 2 piece design can be positioned on pack shoulder straps, vests or clothing. Automatic, “no-look” operation, Designed to eliminate tube snags- magnet holds securely for normal use yet allows the tube to pull free when overstressed.