DIM: 4"H x 4"W x 2"D folded, 8" DIA x 11"H unfolded, 500 cu. in.
Mister big boy Mega here also has all the same core dump pouch features and more. Despite the obvious change, that it is freakn' BIG, there is a removable leg strap included to help secure and stabalize once deployed.
Also the main closure is by non-elastic cord and cordlocks rather than shockcord. With this size you can get into bigger items such as gas masks, but in general works great for anything of large size yet minimal weight. For the civi side these work great for groceries. Back to more MIL uses, also works great as a prisoner hood. In that use the cordura perhaps is not the most breathable material, but I think you get the idea. Currently available in OD, Khaki, Black, ACU. Malice clips not included. Check out the animated gif link for a quick foldup demo.