Update!

Sale 1: https://backpack.tf/profiles/76561197966756586#!/compare/1624492800/1624579200

https://backpack.tf/profiles/76561198055533871#!/compare/1624492800/1624579200

Cheems like it sold for 11 keys

Sale 2: https://backpack.tf/profiles/76561198055533871#!/compare/1624579200/1624665600

https://backpack.tf/profiles/76561198137566942#!/compare/1624579200/1624665600

Use on Heavy Duty Rag.

Sale 3: https://marketplace.tf/items/tf2/309;5;u36;strange - 24.99/1.89 = ~13

Sale 4: https://backpack.tf/profiles/76561198026871080#!/compare/1625529600/1625616000

https://backpack.tf/profiles/76561198095022965#!/compare/1625443200/1625529600

Bulk/was used there.

Sale 5: https://backpack.tf/profiles/76561199160852295#!/compare/1630540800/1630627200

https://backpack.tf/profiles/76561198095022965#!/compare/1630540800/1630627200

13 pure.

Sale 6: https://backpack.tf/profiles/76561198841279602#!/compare/1623715200/1623801600

https://backpack.tf/profiles/76561198280524116#!/compare/1623715200/1623801600

?

Additional by Xergoyf:

https://backpack.tf/item/2737291286 - a few new sales but nothing traceable/usable

https://gladiator.tf/listings/60d47b35995e3004c3d73cac

Wayne's b/o was 11 so that confirms that sale. There was also another seller that was selling off for around a month after with no luck @ 11.

I would include 11 here, seems to be more than enough support for it.

Classies: https://i.imgur.com/d3HMRNW.png. 11-13 ig