HydraPak PackFlask 500 & 750ml

Choose the HydraPak PackFlask because it is the only model we know of that attaches directly to backpack shoulder straps without daisy chain loops, and can even mount to a sternum strap. Instead of G-hooks, it uses a pair of Velcro bands that wrap around the shoulder straps. As such, it will work with Osprey packs, or basically any model with volumized shoulder straps. The drawback to this design is that there is no hard vertical stop to prevent the sleeve from gradually drifting down. The good news is that the Velcro bands seem to create enough pressure to keep it in place, barring an aggressive tug. Another drawback is that the opening is not stiffened, so it can be difficult to set the bottle back into the sleeve one handed. Notable, this stretch mesh sleeve comes with a complimentary bit valve soft flask with which it was designed to be paired, and is available in three versions: a 500ml, a 750ml and a 750ml with filter (PackFlask+). Because the 750ml is a bit too wide, we recommend the 500ml size and buying a filter separately; sadly the + version is only for available with 750ml.

• Price: $42, $45 ($72 w/ filter)
• Weight: 2.8 o, 3.3, 4.2 oz
• Mesh: Stretch
• Attachment: Two Velcro straps
• Bottle Retention: Top cinch closure
• Intended to Fit: Short & wide soft bottles that it comes with, 500 or 750ml
• Fits Half Liter Soft Flasks: Yes
• Pros: Fits shoulder straps without daisy chain loops, like Osprey. Comes with own soft flask. Good value all-in one system if you add the filter. Also works as a gear pocket. Nice bite valve.
• Cons: No hard vertical stop to prevent it from sliding down. Unstiffened opening rim requires two hands to put flask back in. Mesh snagging durability concerns.