TIMOTHY F I believe they can. I have a Mammut Heron Light 65+15 Backpack, on which I front-mounted my Marmut 0 degree mummy sleeping bag on the outside, and I was able to cover it all with my Mountainsmiuth Rain Cover (size large). I still had plenty of cinch to take up afterward, so it was snug on the pack and bag.

BARRY B The Mountainsmith Extra Small (20" X 14" X 7.5") fits my Mountainsmith Day TSL Lumbar Pack (13" x 12" x 8") just right.

JEN O I bought the large size for an Osprey 65 and it works great. Not sure depth is an issue per se as it conforms to pack...Great value and fits well even with a full pack.

RICK L With the Kelty Redwing 50 being 3100 ci, you could go with either small which fits 2500 - 3500 ci pack or medium which fits 3500 - 4500 packs. I have both the medium and large, which I use on our Mountain Smith packs and I went by the size of the packs ci for fitness, they fit nice and pack up small. The medium fits both our day pack and my wife's pack. Hope this helps

TRENT G The bigger, the better imo.........either of the larger sizes will work fine on that pack as they adjust with a shock cord ;)

STEVEN W I bought a size small for my North Face Terra 45 pack. It fits perfectly even when the pack is totally stuffed. I think it would work for a slightly bigger pack, but you could always play safe and go a size larger.

TRENT G The bigger the better....especially if you plan on having lots of things strapped to the outside of the pack plus sleeping bag.....I think the large size is what you need. It has a wrap around cord with a cord lock that can be sinched up around the pack or frame so the extra fabric when the extra stuff isn't there....nice pack cover......keeps everything nice and dry! Go BIG!

CAROLE B I'm assuming it's a 64 liter pack, but I have an XL for my Mountainsmith Circuit 3.0 which fits with little extra room when the pack is full. That's around 300 cubic inches larger than yours though, so I would say the XL should fit. You can measure height/width of your full pack (with sleeping bag, etc on bottom) to be sure that it will fit in. If it's a little bit larger in one dimension (a couple inches at most) just make sure you have lee-way in the other dimension. The only problem i have is getting the cover to pull all the way to the straps on the bottom with a very full pack, but that's with extra stuff on the outside.

Zack W The small would be fine. Enjoy it! Zack.

CAROLE B I have the XL cover which should fit your luggage. The dimensions are not rigid, so the little extra width shouldn't be much of a problem and easily compensated for by the extra length. However, if your luggage is a suitcase I would not recommend a backpack cover. It would make the suitcase impossible to carry or roll and would only cover 5 of the 6 sides.

BRIAN W It should work fine. It has a nice draw string to cinch the cover tight

TRENT G Sure, it should work if you buy the extra large size. It should stretch all the way around all four corners of the luggage you have ;)

SunnySports S Yes, you should get size small. Stay safe and have fun out there! Neal

SunnySports S Even the largest Mountainsmith may not fit. This pack is 37" high & the large covers 31.5". I suggest the Kelty rain cover, our SKU # KLTPRCLR. You"ll be guaranteed a good fit.