Your one-day skipass for Saturday for 20€ or 30€ (senior, kids, adults) depending on the day of payment :
If you pay your Saturday ski pass on Thursday or Friday (before midnight), the prise is 30 €.
If you pay it on Sunday, Monday, Tusday or Wednesday (before midnight), the price is 20 €.
There is no exchange or refund. It is not transferable either.
Try it here => Saturday Extra
Be careful to start skiing on Valmeinier's side of skiresort (first skilift must be taken in Valmeinier).
Otherwise you are blocked on control terminals.