This is a magnetic clip for Hydration Bladders with tubes from 9-10mm in diameter and for pack webbing of 20mm. I found other designs but found them bulky and not as secure. I designed this one so the magnets on the clip protrude slightly and are recessed slightly on the base. This creates a nested approach which holds them securely and resists shearing forces a bit. It takes 3 12x2mm magnets in the base and 2 in the tube holder. Super glue is needed to secure the magnets permanently although it's not a loose fit.