Critical Mass Top Load / Panel Load / Roll Top / Bayonet......For those that like the options of a heavy load carrying panel loader but don't need a full panel loader, AND like the option of top loading / roll top simplicity. Click images. This model is the same volume as a S-CM II with about a 46" circumference. That gives it a volume of about 4300 cuin at the 26" level in the second row of photos. Overall volume is about 6500 cuin with top pocket. Of course, they can be made smaller. Standard style CM packs. MB Super