Item history for reference

https://backpack.tf/item/9730363430

Sale 1

https://backpack.tf/profiles/76561198075045529#!/compare/1614124800/1614211200

https://backpack.tf/profiles/76561198071726259#!/compare/1613865600/1614211200

Seems to have been 11 keys

Sale 2

https://backpack.tf/profiles/76561198071726259#!/compare/1614211200/1614297600

https://backpack.tf/profiles/76561199132162102#!/compare/1614297600/1614384000

Sold for 18 keys as you said

Sale 3

https://backpack.tf/profiles/76561199132162102#!/compare/1614297600/1614384000

https://backpack.tf/profiles/76561198420097719#!/compare/1614211200/1614470400

I only see one key matching ID

https://prnt.sc/10arg2d - these match history though so I guess sure 3 keys in adds

https://backpack.tf/suggestion/5fb469d774e487334a1ab7d3 - this is kinda outdated

The sale used in this suggestion:

https://backpack.tf/profiles/76561199068665221#!/compare/1605571200/1605657600

https://backpack.tf/profiles/76561198035669902#!/compare/1605571200/1605657600

It's from November so a month outdated now

https://backpack.tf/item/2399621244 - couple histories to check to update the bombing run

Given that the bombing run will likely be less than 18 keys

This means that the sales here are 11 >> 18 >> less than 15 keys

I would hold off suggesting this for the time being and wait for another sale