This is a waterproof Memory card holder by Kora, holds 12 SD (most common camera cards) and 12 micro sd cards(go pro , drones , phone camera).
It is crush proof, water proof, and dust proof for $8.99. (on Amazon Prime shipping is free)
If you find yourself loosing cards or getting your priceless images damage(like I have in the past) or need to carry extra cards with you this is an excellent solution.
Here is the amazon link.