Please note, Mars Project 2.0 orders start shipping June 5th.The Mars Project 2.0 Prime Meridian features side LandSpeederA(R) Systems attachment points. This modular attachment system allows for easy and secure attachment of modules to the side of the bag creating an interchangeable platform for add-ons and future expansion.The UX Expansion Module comes in two sizes. The UX1 offers 1 liter of expansion with each module while the larger UX2 offers 1.75 liters of expansion per module.Made in the USA UX1 Measures 8.75" x 4.25" x 1.5"UX1 Measures 8.75" x 4.25" x 3"