Stormproofing

https://backpack.tf/item/6105721455

Sale 1) Sold for 18 Keys

https://backpack.tf/profiles/76561198132527164#!/compare/1555632000/1555718400

Sale 2) Sold for 12 Keys + ~2 Keys of Items

https://backpack.tf/profiles/76561198829961486#!/compare/1556582400/1556668800

12 + 2 = 14 Keys

Sale 3) ?

https://backpack.tf/profiles/76561198125894529#!/compare/1556582400/1556668800

https://backpack.tf/profiles/76561198093707809#!/compare/1556582400/1556668800

Sale 4) ?

https://backpack.tf/profiles/76561198093707809#!/compare/1556668800/1556841600

https://backpack.tf/item/6797789686

Sale 5) Bulk sale

https://backpack.tf/profiles/76561198838788284#!/compare/1555027200/1555113600

Sale 6) Bulk sale

https://backpack.tf/profiles/76561198218628708#!/compare/1556668800/1556841600

https://backpack.tf/item/6120514682 - Gambling, gambling, and more gambling

https://marketplace.tf/items/30863;5;u29 - Sold for $27.99 when Keys were ~$1.79 each and $26.99 when Keys were ~$1.79 each

https://marketplace.tf/items/5021;6/Mann%20Co.%20Supply%20Crate%20Key

27.99 / 1.79 = 15.63, which rounds to 16 Keys

26.99 / 1.79 = 15.07, which rounds to 15 Keys

Calling 18 high because of Sellers -> https://imgur.com/a/vFhnMYB

https://backpack.tf/item/6105721455

https://backpack.tf/item/6805000519

https://backpack.tf/item/6797789686