i have not personally ever used them as my pack is too big as it is to justify bringing something like that with me because i can barely fill it as it is but i have seen a few reviews about the aarn packs which the snypack kinda remind me of. give it a look through!
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Modern civilized man, sated with artificialities and luxury, were wont, when he returns to the primeval mountains, to find among their caves his prehistoric brother, alive and unchanged. -Guido Rey