They are called flex packs (U23s: eight games for $60, Sounders Women: 12 games starting at $100).
The cool thing about the flex packs is you can use them for either team and also allot them however you like — e.g. letting a friend use one. Check out the teams’ websites for more information. The flex packs also include admission to exhibitions and playoff games, if applicable.
As a reminder, The Sounders FC U-23s are the local Premier Development League affiliate for the MLS Sounders as part of the youth development program (note: DeAndre Yedlin played for the U-23s a couple summers ago). The U-23s will play home games at Sumner High School, Starfire Stadium, Curtis High School and Tumwater High School next season, with a full schedule set to be released soon.