The National Football League (NFL) is once again dabbling with non-fungible tokens (NFT), launching a series of card-themed collectibles tied to its upcoming player draft on Thursday.

The collection is live on the league’s Polygon and Flow-based marketplace, which it unveiled in November 2021 and has since been used for various playoff game ticketing promotions.

The NFTs will also be given out to members of this year’s “Inner Circle” club, which includes fans selected to represent each team on draft night.

A representative of the league told CoinDesk it has given out more than 500,000 NFTs tied to ticket purchases since the marketplace’s release. Of those 500,000, around 210,000 were directly interacted with by their owner, a 42% figure the league considered a win in terms of engagement.

“Those are just the ones we gave out for free, so we were impressed by the engagement numbers for sure,” Sam Rubinroit, the NFL’s director of club business development, told CoinDesk in an interview. “A good number of the NFTs we released for purchase sold out within 24 hours of their release.”

Rubinroit said the ticketing collectible platform is still very much in its “test and learn phase,” with larger plans cued up for the upcoming season. NFTs from its initial “Regular Season Clubs” collection were one point trading hands for thousands of dollars a piece, but have since cooled off to the $300-$600 range for the more popular teams.

Read more: NFL Teams Test the Waters of Crypto Fan Tokens

The marketplace is just one of many NFT waters the league has dipped itself into in the last year, the most notable being a partnership with NBA Top Shot maker Dapper Labs to create NFL All Day. Both Top Shot and All Day are built on the Flow blockchain.

The league’s official blockchain partnerships policy remains lucid and developing, but has seen movement in the realms of fan tokens and crypto endorsements in recent weeks.

The league’s players association (NFLPA) has a few crypto-related partnerships of its own, including an NFT tie-up with sports betting giant DraftKings and a partnership with the metaverse game Upland.

UPDATE (April 28, 16:50 UTC): Corrected that the collection was released on the Flow blockchain, not Polygon as previously stated.