Bags such as this one are often very roomy. This duffle bag is made exclusively from polyester and it has a volume of 25 litres.
From Nike
Nike Brasilia 9.5 Training Duffel Bag (Extra-Small, 25L) - Black - Polyester - ONE SIZE
House of Fraser
Nike Brasilia Duffel Bag (Extra Small) - Black
This product is also available at 1 unverified store.