Starbucks customers across hundreds of locations in the United States started their weeks off with a surprise: Their beloved Frappuccinos and iced espresso drinks served in paper cups, not plastic.

Tall, grande, venti—cups for each drink size have mysterious lines on the sides. What exactly are those markers used for?

Starbucks just released five new merchandise items in honor of cherry blossom season. The limited edition collection is available now until supplies last.