I felt like an accountant calculating stuff for this.

As far as I know ( had others check with premium), this is the only sale of this hat with this effect.

Sale 1

For 143.22 Keys (USD 338.01) on the SCM on 29/10

https://i.imgur.com/6pkBRCg.png

https://i.imgur.com/o6eMXoc.png

https://backpack.tf/item/7266141609

https://steamcommunity.com/market/listings/440/Unusual%20Berlin%20Brain%20Bowl

Average Key Prices = USD 2.36 on SCM for 29/10

https://i.imgur.com/WGqFpdM.png

https://steamcommunity.com/market/listings/440/Mann%20Co.%20Supply%20Crate%20Key

Hope you're ready for some math

12 AM Average Price 2.37 | 202 Sold

1 AM Average Price 2.36 | 295 Sold

2 AM Average Price 2.35 | 165 Sold

3 AM Average Price 2.37 | 172 Sold

4 AM Average Price 2.37 | 282 Sold

5 AM Average Price 2.37 | 121 Sold

6 AM Average Price 2.36 | 143 Sold

7 AM Average Price 2.35 | 213 Sold

8 AM Average Price 2.37 | 201 Sold

9 AM Average Price 2.36 | 147 Sold

10 AM Average Price 2.36 | 100 Sold

11 AM Average Price 2.37 | 192 Sold

12 PM Average Price 2.36 | 122 Sold

1 PM Average Price 2.34 | 283 Sold

2 PM Average Price 2.37 | 103 Sold

3 PM Average Price 2.36 | 133 Sold

4 PM Average Price 2.36 | 123 Sold

5 PM Average Price 2.35 | 189 Sold

6 PM Average Price 2.35 | 241 Sold

7 PM Average Price 2.35 | 258 Sold

8 PM Average Price 2.35 | 127 Sold

9 PM Average Price 2.34 | 128 Sold

10 PM Average Price 2.35 | 136 Sold

11 PM Average Price 2.35 | 449 Sold

Total Price USD 10674.88

Total sold 4525

Average Key price on 29/10/2018 = USD 2.36

338.01 (USD Spent on hat) / 2.36 (USD worth of key on 29/10) = 143.22

Rounded to 143

So did some more digging, this hat is a 1:1

https://backpack.tf/premium/search?item=Berlin%20Brain%20Bowl&quality=5&tradable=1&craftable=1&australium=-1&particle=114&killstreak_tier=0

Unless someone is hiding others in a private bp.

While 10 Doorway Bowls & 5 Opening Bowls exist

https://backpack.tf/premium/search?item=Berlin%20Brain%20Bowl&quality=5&tradable=1&craftable=1&australium=-1&killstreak_tier=0&particle=116

https://backpack.tf/premium/search?item=Berlin%20Brain%20Bowl&quality=5&tradable=1&craftable=1&australium=-1&killstreak_tier=0&particle=115

So this is the only sale of a 1:1 item