These bags are on sale, use coupon code 289QG5TM (works on multiple quantities)
https://www.amazon.com/dp/B01MRJNMM8?th=1 10 liters, yellow – $7.39 after coupon
https://www.amazon.com/dp/B01N8ZK867?th=1 20 liters, blue – $11.99 after coupon
https://www.amazon.com/dp/B01GCMHVGK?th=1 10L + 20L = $17.59 after coupon
-100% WATERPROOF MATERIAL
-WITH ADJUSTABLE AND REMOVABLE SHOULDER STRAP
-DURABLE AND STRONG