I've show a ton of these on here, especially in my group breaks. They're $5.99 and they have 4 packs of 5 cards. Typically you get 1 blue parallel, 1 UD 20th insert, and 1 relic. The relic checklist is decent, so I love picking these up.
The base cards are purple, which don't do much for me:
The blue parallels are much better:
What's the farthest anyone ever got on the 20th Anniversary set?
Lastly the relics:
The Big Unit doesn't get nearly enough hobby love. He's in the conversation with the best pitchers of all time.