The Accessory Side Pouch would go very well with the Pantac Molle 3-Day Pack Set as that set has many places for attachments. Its dimensions are H24cm X L37cm X D10cm enough to fit any spare bits and bobs you may have around that you wish to keep safe and secure.
It's an incredibly large backpack as it's main purpose is to haul around large luggage. Inside is one big space with padding up against your back for protection. On each side are 2 pockets both, 20 x 10. There is a MOLLE section at the back near the bottom if you wish to attach anything to it that may find useful!