3 exists , 1 active .

https://backpack.tf/item/4161648529

Sale 1 (17/3) -

Sold it for $27.5 on marketplacetf

$27.5 / $1.98 = ~13.8keys -> 14 keys

https://marketplace.tf/shopitem/76561198054758757/30625;5;u57/Terror-Watt%20Physicians%20Protector

Sale 2 (15/2) -

Sold it for 11keys + 18refs (key was worth 37refs on 15/2) = ~11.4keys -> 11 keys

https://backpack.tf/suggestion/5a77211a44325a0ee3501539

https://i.imgur.com/KJlRXTG.png

Sale 3 (8/2) -

Sold it for only 10 keys

https://backpack.tf/profiles/76561197971983043#!/compare/1517875200/1518134400

Sale 4 (???) -

https://backpack.tf/profiles/76561197971983043#!/compare/1518393600/1518480000

Disappeared for unknown reason , 15 keys sale was the stahlhelm .

Sale 1 = 14 keys . Usable

Sale 2 = 11 keys . Usable

Sale 3 = 10 keys . Unusable . Lowest buyer at 10.25 keys now .

Sale 4 = ???

Old suggestion : https://backpack.tf/suggestion/5ab8e031cf6c75032d540b15

I forgot that we can't suggest unusual with .5