What criteria should I use to choose among the three sizes of the Dyneema Trail Pouch?

While the size increases noticeably, the weight hardly differs. The S size has a width of 16.5cm, height of 14cm, and width of 4.5cm, and the L size reaches a width of 20cm, height of 24cm, and width of 6cm^[1][2]. On the other hand, the weight is 8g for the S size, 9g for the M size, and 12g for the L size^[3]. The difference in weight is very small. Since even the largest L size is merely 12g, there is no need to push yourself to stick to a smaller pouch just to reduce backpack weight.

In the end, the criterion for selection becomes the volume and height of the items to be packed, not the weight of the pouch itself. Hegiorsak's trail pouch is divided into three sizes: S, M, and L^[4]. The S size with a width of 4.5cm is suitable for neatly organizing small-volume belongings that are taken out frequently, such as car keys, lip balm, and trail snacks^[5]. The M size, measuring a width of 18cm, height of 17.5cm, and width of 5.5cm, is appropriate for holding items with some thickness, such as power banks, charging cables, or small toiletries^[6]. The L size, reaching a width of 20cm, height of 24cm, and width of 6cm, is good for gathering and storing rather bulky gear in one place, such as thin windbreakers, spare socks, or cooking gear^[7].

hmmm, putting aside worries about the weight of the pouch and considering only which items to group together in your backpack makes the choice much easier.