• Online:
  • URL for this product:
  • From the U.S. and CanadaCall 1-800-426-4840
  • Mon. through Sun., 4 a.m. through 11 p.m. PT.
  • InternationalCall 1-253-891-2500
  • Mon. through Sun., 4 a.m. through 11 p.m. PT. English language only.

Mountain Hardwear Fluid 6 Pack

This item is currently sold out or unavailable online.

Or, may we suggest shopping for similar items:

Shop more Running PacksShop more Mountain Hardwear

This page is provided for reference to historical product information.

  • Wide, well-ventilated mesh shoulder straps and a breathable back panel offer all-day comfort, even during intense activity
  • Panel-loading main compartment holds a hydration sleeve with dual drink-tube ports (hydration reservoir sold separately)
  • Thoughtfully placed pockets on the shoulder straps and sides of the pack offer quick access to energy bars, gel packs, water bottles and other gear
  • On-the-fly compression lets you adjust the load stability while wearing the pack; front bungee secures a rain shell or other bulky items
  • The Mountain Hardwear Fluid 6 pack features reflective accents for increased visibility


Item 828973


This item's hot - and it's only available online.

REI Membership

Mountain Hardwear Fluid 6 Pack Specs
Best use
6 liter
365 cubic inches
10 ounces
0.28 kilograms
16 - 22 inches
27 - 39 inches
Ripstop nylon
5 + main compartment
17.5 x 8 x 6.5 inches
Frame type
Gear capacity (L)
Gear capacity (cu. in.)
Weight - metric
Adjustable torso
Fits torso
Fits waist/hips
Suspended mesh back panel
Pack loading
Pack access
Number of exterior pockets
Sleeping bag compartment
Raincover included

Mountain Hardwear Fluid 6 Pack

Loading Ratings & Reviews...

Rated 5.0/5 based on 1 reviews
Rated 5out of5
by fromIdeal for long runs... I bought this hydration pack for marathon training. I also bought the Osprey Viper 4 and the CamelBak Octane XCT to compare. Those last two were returned. Overall, I took a risk on the vest hybrid after swearing by CamelBak packs for almost 20 years. It paid off. I love it. Mountain Hardwear did a great job with this one. It fits 100oz of water, my phone, and some nutrition, but could fit a midweight shell with no issue. Now, the tl;dr part... With any hydration pack, you're going to feel restriction somewhere. The biggest difficulty in deciding between the XCT and Fluid was whether to restrict the waist or the chest/shoulders. It was pretty close for me, but I went with the Fluid because overall it was less restricting. Moving the upper body is much less important in running than moving the lower body, so restricting the waist is less desirable. I rated these on a restriction scale from unhindered movement (0) to completely throwing off my entire running form (10). This is completely subjective. Fluid 6: Shoulder restriction 3, torso 1, hips 0. Fits like a vest, snugly against the upper back, and allows for free movement from about midback down. Since it's an upper back pack, there isn't the mid-low back sweat accumulation, which allows for a nice breeze. In 90 degrees, I didn't feel especially clammy on my back as I usually do with packs. I was worried about pinch-points because of the thick shoulder straps, but didn't get any on my 12 mile run. The little elastic bands on the shoulder strap are good for arranging your hose where you want it. The elastic pocket on the front can fit my beefy iPhone with Otterbox Defender case securely. The actual cargo area is open to the zipper and has an elastic-rimmed sleeve for the bladder. I could probably fit a tube and bike pump and tools in if I needed, too, plus a shell in the elastic bands on the back. There are two side pockets, as well, but these are hard to reach on the run. Despite this, the whole pack can be cinched down with two-point shoulder strap connections and those elastic band on the back. There was almost zero sloshing. As the bladder drained, a quick pull up on the shoulder straps down near the hips tightened it back up well. It's also very adjustable across the chest with two straps and 15 different chest strap positions (yes, I counted). CamelBak XCT: Shoulder restriction 1, torso 3, hips 2. Very lightweight. 100 oz, which is good. The weight of the water was distributed near the mid-back, but lower than the Fluid. There was restriction of both shoulders and hips, though the hip straps were well-fitting. If I was looking to double for a biking pack, this might be it (though I'd probably go with the Octane 18 for the extra cargo). There was little cargo room for anything larger than my fist on the back pocket, but the hip pockets were bigger than any other pack's I've seen. A very close second place. Viper 4: Shoulder restriction 3, torso 3, hips 1. Don't bother. Bulky, unadjustable strap system across the neck and shoulders. (I'm 6'3", jacket size 42L). Seems to have extra weight and too much rigidity, so it doesn't cinch down against my body. Waist straps are meager and uncomfortable. LidLock is useless for running (it's for helmets). No cargo room. Front pockets aren't that great. Would be a decent road biking pack, but not for running. Bottom line: Fluid 6 is a well-designed, low-cost option for distance running.
Date published: 2012-08-13

Ask a question and have it answered by REI product experts and fellow outdoor enthusiasts. Need immediate assistance? Use Live Help.

Loading Questions & Answers...

How are we doing? Give us feedback on this page.

      FREE SHIPPING With $50 minimum purchase

      • Join REI today!
      • REI Membership
      • REI member benefits include an annual refund (typically 10% on eligible purchases).
      • Join REI today!
      • Sign up for REI Gearmail®
      • and get 15% off selected items!
      • Store Locator
      • Locate an REI store near you.
      • Find a Store
      © 2014 Recreational Equipment, Inc. All rights reserved. REI, the REI Tree and Mountain design, Novara, and
      REI Adventures are trademarks of Recreational Equipment, Inc.

      Find REI on: FacebookTwitterYouTubeFlickrMobile site