After being considered underdogs against the Atlanta Falcons and the Minnesota Vikings, the Philadelphia Eagles will embrace that role one more time against the New England Patriots at Super Bowl LII. So will their passionate fans, who donned dog masks during the Eagles’ blowout victory over the Vikings in the NFC Championship Game on Sunday in Philadelphia.

Since Eagles players Chris Long and Lane Johnson wore the masks after an upset win over the Falcons on January 14, the latex German shepherd masks have become the hottest product in the City of Brotherly Love. Three days after the game, one Amazon vendor sold out of its “Latex German Shepherd Dog Masks” inventory, USA Today reported. Despite doubling the price of its masks to keep up with demand, manufacturer CreepyParty also sold out of its entire inventory, ESPN reported.

Because CreepyParty’s factory is based in China, maintaining supply has been a major issue. After its initial inventory of 300 masks was emptied, the company bought 300 more masks from other distributors at a higher cost. Retail price bounced from $16 to $39.99.

After restocking last Monday, CreepyParty sold 200 masks in six hours, and by last Wednesday, they were all gone. But Eagles fans continue to hound the manufacturer with emails requesting the masks, prompting CreepyParty to address the situation on its website.

“Once the Philadelphia Eagles win the next football game, we will send all of our products to America with the fastest logistics channel. We estimate the earliest date that you can order the mask is 1/25. We can ensure that you would get the dog mask before the Super Bowl,” CreepyParty posted.

The Eagles organization encouraged fans to wear the masks during the NFC Championship Game with the caveat that they take them off while going through security at Lincoln Financial Field.

The underdog moniker stems from Eagles starting quarterback Carson Wentz being sidelined with an injury, leaving backup quarterback Nick Foles to lead the birds to the promised land. As three-point underdogs to the Falcons, the Eagles were the first number-one seed in NFL history not to be favored in its first game of the postseason. They were also considered 3.5-point underdogs to the Minnesota Vikings.