This is a drying hook and spreader for a Camelbak Crux hydration bladder.
It should fit most bladders - Camelbak and other brands - that have a removable hose
The hook captures the bite valve of the hose and the bladder connector to hang them for drying. The spreader clips over the filling port and keeps the bladder open for air circulation.
It is inspired by: http://www.thingiverse.com/thing:1051302