The Trion collection consists of Mammut's versatile range of backpacks built for trekking and mountaineering, and the Trion 50L Backpack is the second-largest pack in that backpack. Its Contact U Frame consists of cushy EVA and air channels for four-season ventilation. The waist belt is removable customized support if you're carrying a lighter load. There are external attachments for skis, ice axes, trekking poles, and even climbing ropes. The Trion 50L is compatible with hydration reservoirs, and there are multiple pockets to organize smaller valuables.