It's a joke that you only get these four balls on one day during the Corona period, and then only one ball per purchase. As a customer, you would have to go back to the store for every 20 franc purchase (i.e. split the purchase and go through the store and to the checkout five times) to even have the chance to get more than one color, or at least have balls to swap. Very disappointing of Migros that, if they are giving away the balls like this, they don't at least only give away special balls on this day. So one pack per 20 francs, so that you at least get a few packs when you shop.