Think of the ALPHALITE as our “close quarters” trail pack.
The volume size 27L is ideal for 2-3 Days hiking, section, or thru hikes where resupply points are less frequent, or for equipment flexibility. When the extra volume is not in use, the ALPHALITE 27L top can roll down enough to make the overall size of the pack similar to 22L, but that additional space can come in pretty handy when you need it.