Duffel bags are easy to squeeze into tight spaces. One of the materials used to make this bag is polyester and it holds 31 litres.
From The North Face
The North Face Base Camp Duffel - Extra Small Tnf Black-tnf White-npf One Size male - TNF Black-TNF White-NPF (One Size)
Scandinavian Outdoor Store
The North Face Base Camp Duffle XS
This product is also available at 2 unverified stores.