7 keys pure:

https://backpack.tf/item/7405729043

https://backpack.tf/profiles/76561198011321852#!/compare/1599955200/1600041600

https://backpack.tf/profiles/76561198056288494#!/compare/1599696000/1600041600

Untraceable in seller's side, untraceable sale in buyer's side

https://backpack.tf/item/7406428838

https://backpack.tf/profiles/76561198934156457#!/compare/1598659200/1598745600

https://backpack.tf/profiles/76561198799345159#!/compare/1598486400/1599523200

Bot.tf stats sales:

https://imgur.com/UsTg4Hn

https://bot.tf/stats/item?def=31024&q=5&ef=Orbiting%20Planets&craft=1&aus=0&ks=0&source=browser_script

Can't trace the sale but Bot.tf indicates 6 keys 44 ref, ~7 keys

https://backpack.tf/profiles/76561198341171690#!/compare/1598054400/1598227200

https://backpack.tf/profiles/76561198280524116#!/compare/1598054400/1598227200

6 keys 37 ref (6 keys 24 show but the rest was most likely instantly retraded) =6.85 keys ~7 keys

https://backpack.tf/profiles/76561198341171690#!/compare/1598832000/1598918400

Bougt for 6 keys 1 ref pure:

https://backpack.tf/profiles/76561198341171690#!/compare/1598227200/1598313600

Excluding 6 keys because of generic Unusual Crack Pot buyers at 6.16-6.34 keys, going with 7 flat