FITLY Minimalist Running Pack | Unisex Backpack with XS-S, Black

The Sub45 and the Sub90. The Sub45 is designed for shorter runs, and does not house the FITLY flask and tube. XS/S is 26 in to 31 in (67 cm to 78 cm) & M/L/XL is 31 in to 40 in (78 cm to 102 cm). The architecture ensures no item will bounce around.