Made specifically for the Marco Polo-system, yes, but of course you don’t need the Marco Polo to take advantage of this bag. But it does have a dedicated pocket that holds the Marco Polo or any other of C&F’s standard fly boxes. I believe the standard boxes also are available empty, if you just want to pack some selected tools.
Apart from the dedicated pocket it has several pockets - not littered with them as some fly tying bags are. A big zippered one in the bag - arge enough to hold even the largest of capes or saddles. In front of this another zippered one and on this, a few pockets for smaller items (bags of dubbing - that sort of stuff).
On the other side the dedicated Marco Polo-pocket and to the right (on the PoD) of this, a vertical pencil-case-like zippered pocket. In the case of what I have packed for next week, I simply have tubes packed in there. I should also pack a pair of glasses, now I come to think of it. And of course you can stuff plenty of stuff in the main compartment as well, between the two sides. The bag closes with a nice, sturdy zipper.
If you travel a lot or just need to bring fly tying on a trip some where, this bag really does complete the Marco Polo-system and I’m very satisfied with mine. As you can see, for next week I’ve just packed for some chartreuse-blue-black Sunrays (a variant called the IceRay, since the colours are based on The Iceman). Pack light, don’t expect that you’ll be able to tie for the entire season. I usually pack for one or two patterns.
Have a great weekend!