Last we heard from Starbucks, the coffee and sugary drinks giant updated its rewards program to allow members to snag free merch when they save up enough points. This week, Starbucks was back in the news for merch, this time for its new eco-friendly, color-changing branded cups that are so popular, stores are struggling to keep them in stock.

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Color Changing Cups ????Of course I had to call every single @starbucks store to find these Babies?? so glad I was able to snag a box, they are so pretty OMG . . . #starbucks #starbuckscups #starbuckscoffee #starbuckstumbler #starbuckscolorchangingcup #starbuckslimited #starbuckslimitededition #prettycups #cups

A post shared by ????? ????♡?? ??????? (@dessinicholedesigns) on Apr 30, 2019 at 5:04pm PDT

the all new @starbucks color-changing cold cups in 3D ✨ pic.twitter.com/tXUnoK18yX

— con artist (@connorsurdi) May 2, 2019

Starbucks launches a number of branded collections every year, and most are released around holidays and specific seasons—like these floral prints from September and the pink and rose gold cups and tumblers. But this one, in particular, left fans scrambling to find stores that still had the cups in stock.

The cups come in packs of five and include the colors rose, citron, sky, apricot and arctic, plus colored lids and straws, so customers can switch it up however they’d like. The other neat part is that they have an ombré effect when cold beverages and ice are added. According to a USA Today article, this is what you can expect the cups to look like when they transform:

• Rose: light pink to coral red
• Citron: yellow to emerald green
• Sky: light blue to cobalt blue
• Apricot: light orange to tangerine
• Arctic: teal to raspberry pink

The problem, though it’s a good one for Starbucks to have, is that most stores are sold out of the cups. Twitter users are even suggesting calling local stores before traveling far and wide to find them. Otherwise, those who were able to get their hands on the branded cups are re-selling them on Etsy and eBay at much higher prices (the originals go for $16.95 per pack).

Another Twitter user even tweeted that her local store was answering the phone ready to tell customers that they were out:

So I called Starbucks to see if they had the color changing cups and she answered the phone with “Hello this is Starbucks on North Main we are out of the color changing cups how can I help you?” …….

— chloe (@chloekling22) May 2, 2019

Clearly, there’s still a high demand for the branded cups. While Starbucks normally announces special limited-edition collections, this one wasn’t as advertised, but was still selling out everywhere. The good news is that there will be a restock, but Starbucks wasn’t sure when. If the restock is anything like the last launch, it would probably be best to keep an eye out for the cups because they could be gone before you know it.