Sale #1:

https://backpack.tf/profiles/76561198114001918#!/compare/1550275200/1550361600

Sold for 15 keys

15 keys

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Sale #2:

https://marketplace.tf/items/48;5;u36

Sold for $26.77 on December 6, 2018

$26.77 / $1.70 = ~15.7 keys

16 keys

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Sale #3:

https://backpack.tf/profiles/76561198114001918#!/compare/1549670400/1549756800

Untracable.

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Sale #4:

https://backpack.tf/profiles/76561198030958701#!/compare/1548547200/1548892800

Sold for 14 keys

14 keys