What size should I get if I'm looking to use this with a regular size synthetic sleeping bag? Currently it stuffs down to about 10x16in. I'm thinking the 15L should be fine, but I'm debating whether or not to get the 20L just in case. Thanks.

Tech Specs:

Material:

eVent 

Closure:

Roll-top with compression straps 

Volume:

[XS] 6/2L; [S] 10-3.3L; [M] 14/4.5L; [L] 20/6.7L; [XL] 30/10L 

Dimensions:

[XS] 6 x 14in; [S] 7 x 16in; [M] 8 x 18in; [L] 9 x 20in; [XL] 10.5 x 23in 

Backpack Straps:

No 

Weight:

[XS] 3.7oz; [S] 4.5oz; [M] 5.2oz; [L] 5.9oz; [XL] 7.4oz 

Warranty:

1 Year 

Country of Origin:

China