Good morning Pilgrim
The Half Fare Travelcard is valid for a year, but we also offer another option, the Swiss Half Fare Card, which is specifically for tourists or individuals who do not have permanent residence in Switzerland.
The Swiss Half Fare Travelcard is priced the same as the Half Fare Travelcard Youth, both at CHF 120. I can understand how your son may have confused the two.
I recommend that your son purchases the Half Fare Travelcard for a year, either online or at any SBB ticket office. Please note that purchasing the Half Fare Travelcard for a year will bind him to a contract. You can find more information here: https://www.sbb.ch/en/tickets-offers/travelcards/half-fare-travelcard.html
I wish you a pleasant day and all the best.
Kind regards,
MichèleP