The duffle with the red ends in this photo (that I previously posted in post 18 a year ago) is one of them, full length zipper. I have used this as a carry on bag on Amtrak several times, the photo shows my carry on luggage just before I got on a train at the end of my Pacific Coast tour.
The photo below (previously shown in post 123 in this thread) shows that duffle with the red ends sitting on top of a larger duffle with blue ends of the same brand and model that I used as a checked bag on Amtrak at the start of that tour, also has a full length zipper.
During the tour, both of this duffels were in the bottom of a couple of my panniers.
Red one is 340 grams, the Blue one is 410 grams. Packs down to almost nothing.
I initially bought these duffels for kayak trips. The hatches on a kayak that you store your gear in are usually pretty small so all of your camping gear is in small dry bags or other small bags. And when you get to a campsite, something like those duffels come in really handy to haul your dozens of small bits of camping gear from the beach to your campsite. Mesh is great as sand does not accumulate in the duffel.
But the one(s) that Indyfabz described in post 162 that is a storage bag for a sleeping bag probably has a draw string end on it, no zipper.
My next trip that I am planning, a duffel with straps on it I think will be preferred for my luggage since I have to have my luggage packed for a bus trip in the luggage compartment, then carry it around with me in a train station, probably for hours, then get on the train. And five weeks later, repeat in reverse.