Backcountry, not SIMMS
This isn't a review about the product. Instead, misinformation by Backcountry.
No volume information between small, medium, and large - at least not in the mobile version of the Backcountry website. All that's shown is 20L... Is this small... Medium... What's 20L?
Actually all of the information is listed right there under "tech specs".
" [small] 10L (611cu in), [medium] 20L (1220cu in), [large] 36L (2197 cu in)
[small] 10 x 13 x 4in, [medium] 16 x 12 x 6.5in, [large] 20 x 13.5 x 8in"