Fire in the Skies.

http://backpack.tf/item/4973315096

Sale 1) Sold for a Haunted Ghosts L'Inspecteur (21.5 Keys) + ~1 Key of Items

http://backpack.tf/profiles/76561198044684270#!/compare/1487462400/1487548800

21.5 + 1 = 22.5, which rounds to 23 Keys

L'Inspecteur Mini

http://backpack.tf/profiles/76561198044684270#!/compare/1491955200/1492041600 - Sold for 21 Keys

http://backpack.tf/profiles/76561198292089126#!/compare/1487203200/1487548800 - Sold for a Dead Presidents Killer's Kabuto (Has a Classies Seller at 21)

http://backpack.tf/profiles/76561198108148076#!/compare/1486771200/1486857600 - Sold for a Max's Severed Head (19 Keys) + 2 Keys + ~1 Key of Refined

Sale 2) Sold for a Miami Nights Vintage Merryweather (25 Keys)

http://backpack.tf/profiles/76561198303303837#!/compare/1487548800/1487721600

Sale 3) Sold for a Circling Peace Sign Glasgow Great Helm (26.5 Keys)

http://backpack.tf/profiles/76561198175249965#!/compare/1490918400/1491091200

Rounding to 27 Keys