Hello @Mattyshmokes
Thank you for your post. Little tip for your next post: you can write the title and separate the message with your question, so is easier for you to get an answer 🙂
The tandem day pass is valid also with a 1-month GA Travelcard for Youth. You can find all the information about this product under the following link: Tandem Day Pass for GA Travelcard Youth | SBB .
I wish you a nice day.
Regards, Giorgia