ZPacks Arc Blast vs. HMG Southwest Pack: UL Backpack Comparison Video

1. One of your main complaints about the Arc Blast is the arc itself.  Personally I don’t use the arc, and let the sack touch my back: better for c of g, and I don’t get too sweaty there anyway.

I suppose I could save an oz by taking the grid and strings right off.

2. The new AB has a grid fabric on the inside of the hip belt, and the belt now wraps around the waist instead of having cuben wings like on your earlier model. This makes it more comfortable, and the belt could be taken off completely if you wish, for a different size, or for someone else to use the pack.

The double adjusters at the waist clip are fantastic for a perfect fit.

3. The shoulder straps no longer attach directly to the sack material, but instead fix onto moveable straps, giving 4” of shoulder adjustment. There are then load lifter straps too, so again you get perfect adjustment.

I find the Arc Blast so comfortable I go for days without making any adjustments to the straps.

4. You can add upper side bags to the Arc for extra volume and convenience.

5. I measured the Arc internal volume at 55 litres, then add on the  volume of all the pockets . I find that sufficient for most summer trekking. I think I might find the huge collar on the HMG a bit inconvenient.

6. Minus points for the Arc Blast : the front mesh is very easy to get holes in, but it would be easy to sew on a dynema panel instead. Indeed, I did sew a dynema panel on the base this year, and have no new holes after 1000 miles. Otherwise there are no signs of wear on the pack. If you don’t need the extra ruggedness of the HMG material in other areas, the Zpacks cuben will be fine.

7. I think the newer Arc Blast is substantially a different sack to the older model. The weight difference of 10 or 11 ozs (see above) between the Zpacks and the HMG is huge.

Zpacks says the main body is 42L and adds in the rest of the pockets to reach 55L.

Volume: 42L main body, 2.5L each side pocket, 8L center pocket, 55 Liters Total

I bought a heavy Gregory pack a couple of years ago, not aware of these lightweight options. When our troop eventually commits to Philmont, I’ll be looking to sell that for something like one of these. I appreciate the review and the above reply.

Sorry, my mistake, I misread my notes. I actually got 41.5 litres, plus the pockets.

Hi John,

Are you the same John that I hiked with on the Colorado Trail this summer?  It appears to be you in your profile picture.  (I also detect a British spelling of certain terms–litre, for example).  Assuming it is indeed you, I recall comparing notes when we camped together.  What I don’t recall is which model Arc Blast you have–do you have the newer version with adjustable torso length or the older version (like mine)?  I concur with most of your points.  However, as I indicated in my video I wasn’t able to get the Arc Blast to fit me comfortably.   Perhaps the adjustable torso might help.  However, the real complaint is the external frame–the internal frame of the HMG Southwest just fits me like a glove, especially since the stays can be molded to fit the wearer’s back.  I did try loosening the arc on my Arc Blast as you have done–however, still no cigar.  I still wasn’t able to get it to fit comfortably.  Too bad, as I really wanted to like the Arc Blast and the 10-13 oz weight difference is, as you stated, quite significant–esp. for someone like me who counts grams, not oz.  In any case, I’m currently reevaluating my pack for next year when I pick up the CT at Twin Lakes.  I may switch to another pack entirely (maybe a frameless one like the Mountain Laurel Designs Prophet in cuben) or the 2400 Southwest (the 3400 was a bit too big in terms of volume), or just stick with what I have.  I will restate what I mentioned in my video–pack fitting is an individual issue and comfort is key, so one should try on a pack loaded up before committing to it for a long distance trail.

Hi David, yes it’s the same me. And yes, my sack is the newer model with the adjustable torso length. Maybe we should have swapped sacks for a few miles!