This is the 4WAY DRY BAG from the crafty Japanese trail specialists Snow Peak.
It's a multi-use waterproof bag, that is constructed from TPU processed polyester with welder crimping technique for durability and waterproofness.
It features a roll-top opening, hidden front pocket, air valve, dual adjustable shoulder straps, and side handle.
The bag holds a 36L capacity, and is made from 100% polyester.