Sale #1:

https://backpack.tf/profiles/76561198088978790#!/compare/1552694400/1555113600

Untraceable.

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Sale #2:

https://backpack.tf/profiles/76561198050518375#!/compare/1547683200/1547769600

Sold for 7 keys.

7 keys

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Sale #3:

https://backpack.tf/profiles/76561198218375863#!/compare/1550016000/1550102400

Bought for ~8.5 keys

8.5 keys

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Sale #4:

https://backpack.tf/profiles/76561198218375863#!/compare/1551052800/1551139200

Untraceable.

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Sale #5:

https://backpack.tf/profiles/76561198185406163#!/compare/1551744000/1551830400

Untraceable.

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Sale #6:

https://backpack.tf/profiles/76561198185406163#!/compare/1553212800/1553558400

Untraceable.

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Marketplace.tf stats:

https://marketplace.tf/items/435;5;u36

Past 90 days:

1x $14.19 ($14.19 / $1.81 = ~8 keys)

1x $21.86 ($21.86 / $1.79 = ~12 keys)

Sales:

8, 8.5, 12. Going with 8 - 8.5 keys.