History 1: https://backpack.tf/item/8993786768

20 keys 12 ref pure:

https://backpack.tf/profiles/76561198025367258#!/compare/1596672000/1596758400

https://backpack.tf/profiles/76561198164651434#!/compare/1596672000/1596758400

23 keys pure (the keys only show in the buyer's compare):

https://backpack.tf/profiles/76561198164651434#!/compare/1599696000/1599782400

https://backpack.tf/profiles/76561198972047944#!/compare/1599696000/1599782400

History 2: https://backpack.tf/item/9025124480

Untraceable sale:

https://backpack.tf/profiles/76561198090739116#!/compare/1596153600/1596672000

https://backpack.tf/profiles/76561198195933333#!/compare/1596067200/1596153600

21 keys pure:

https://backpack.tf/profiles/76561198195933333#!/compare/1596844800/1596931200

https://backpack.tf/profiles/76561198308772967#!/compare/1596844800/1596931200

Untrace/Bulk:

https://backpack.tf/profiles/76561198308772967#!/compare/1597363200/1597449600

https://backpack.tf/profiles/76561198050236510#!/compare/1596153600/1598054400

One sold on marketplace.tf untraceable via item histories: https://marketplace.tf/items/tf2/31094;5;u12

August 23 2020: $49.99/1.81=27.62 keys ~28

Buyers:

Backpack.tf: 1 @ 22.22 keys, 1 @ 20 keys

Marketplace: 1 @ 25/1.85=13.51 keys

20-21 looks a bit low, going 23-28