OXA Fashion via Amazon discounts its OXA UltraLight Dry Sack in various sizes and colors via coupon code "D5KBDIBQ" as listed below. Plus, Prime members receive free shipping. Each sack includes a waterproof phone case. The sizes, with prices after coupon:

• 10-Liter for $9.79 ($4 off)
• 20-Liter for $12.59 ($5 off)
• 30-Liter for $13.99 ($6 off)