I bought this to replace my Osprey Map Wrap which is waterproof material but I found the stitching allows water to seep in under a true downpour.
These just passed the shower test and appear to be bomb proof. So compared to the Osprey...
The Osprey is perfect for strapping to your shoulder strap and keeping as a quick reference.
The Sealines can be rolled and strapped in a similar but less convenient manner. I'm considering strapping on a lanyard and velcro to get the convenience of the Osprey (I really loved that thing till it leaked).
Sealines are more versatile. You can strap it to your boat deck, your shoulder strap, the back of your buddy's pack. It also allows you to view both sides of that map while the Osprey only has one side as see through.
Most important though, these are REALLY waterproof even without seam sealing.
Only lost one star because I've been spoiled by the Osprey shoulder strap attachment and this doesn't have that feature.

I bought this to replace my Osprey Map Wrap which is waterproof material but I found the stitching allows water to seep in under a true downpour.
These just passed the shower test and appear to be bomb proof. So compared to the Osprey...
The Osprey is perfect for strapping to your shoulder strap and keeping as a quick reference.
The Sealines can be rolled and strapped in a similar but less convenient manner. I'm considering strapping on a lanyard and velcro to get the convenience of the Osprey (I really loved that thing till it leaked).
Sealines are more versatile. You can strap it to your boat deck, your shoulder strap, the back of your buddy's pack. It also allows you to view both sides of that map while the Osprey only has one side as see through.
Most important though, these are REALLY waterproof even without seam sealing.
Only lost one star because I've been spoiled by the Osprey shoulder strap attachment and this doesn't have that feature.

Very sturdy and water resistant. Kind of heavy for ultralighters but worth it if your maps keep getting wet somehow. I would say small size will work best for most people.

good product, as the review title might indicate to the layman.

i do not know the appropriate cartography terms, but I folded a 36"x48" map down to the appropriate 4-6 "frame" size in the viewing window of the small. to me, if you can travel that far that fast so as not to not need sleep, there is a possibility that you might need a larger size. i can not.

you also might need the larger size if you have a much smaller scale map with more detail, or you are not planning your route ahead of time.

this thing is waterproof to my bathtub submersion/shower test, although the seal is no more sophisticated than your freezer bag.

the cool thing that makes it worth the money is that the D-rings allow you to attach this to the outside of your pack...this way you dont have to take your pack off for orienteering in a large area...as long as you trust your buddies to lead you to your end game. HA!

i bought one for an upcoming Quetico trip. other than that, take your freezer bags and dont worry about it.

I agree with other reviewers...the sizes are larger than you would think. Small does the job for me. The small is durable and easy to travel with. I like to use it for mountain biking,hiking, and Geo-caching. Great product for the money. Only negative was the zip lock. It was a little difficult to get shut quickly. Other than that good map case to purchase.

but it cracked when it dropped below zero.

I echo the previous review about getting the right size. I purchased the large thinking, bigger would be better, but the large is REALLY large. Would probably work well for attaching to a kayak, but pretty big to use on foot and bike. I also don't really like the zip-lock type closer, which is tough to use if you are taking the maps out often for closer review. Used for adventure racing and didn't get it closed all the way a couple times and got water in it.

i use PDF format maps that i print online and so when i print them they are not on the heavy stock paper that a store bought map is, so this is a must have...if i had to do it over i think i would have purchased the medium size instead of the large.

Case is sturdy and does keep the maps dry. The Medium is big enough for a 1:24000 scale if properly folded for day hikes/Kayak trips. Strength and durability is not a problem with this case. Just watch out for the sizes when ordering!