Hennessy Hammock - Water Collector & Rainfly Tensioner System The HH2O: the next evolution of the idea to tension the fly with rocks or other weights is to clip a funnel onto the two side "O" rings of the rainfly. Another way to make your Hennessy Hammock more useful. Will fit many hydration water bags and your standard sized pop/water bottle thread Packed Weight: 0.85oz / 24gr a pair; Packed Size: 4" x 3" x 3" a pair Size: 2 1/2" x 2 1/2" Per Piece