Can you even remember a time before K-beauty hit the American market and pretty much changed everything? Us neither. The phenomenon has turned us on to ultra-hydrating essences, next-level sunscreens, and yes, oodles of sheet masks — something that has put us on the path to not just glowy skin, but glassy skin. (Yeah, it’s a thing, and for many of us, it’s the pinnacle of goals.)

Another major player co-opted from K-beauty are ampoules — super concentrated serums that generally deliver a higher potency of skin nourishing ingredients. “Ampoules have been a part of Korean skincare for a very long time,” says Soko Glam co-founder and esthetician Charlotte Cho. “They don’t contain fillers like emulsifiers or emollients that cleansers and moisturizers do, so the active ingredients make a big difference in your skin.” Many are made to target specific issues (like dark spots, the effects of aging, or dry skin) and the most hardcore of skin-care fanatics mix and match them depending on their skin’s particular needs of the day. Others — primarily those made by American-based brands — are built for multitasking because that’s how our culture likes to roll.

A couple things you’ll notice about ampoules: Some are packaged in their own little vials or capsules. (This isn’t just about a cuteness factor, but done for one-off use and portability.) They also tend to be more expensive than other serum options offered by a brand. The reason for both one-off packaging and the higher price point? These suckers tend to pack more potent concentrations of top-performing ingredients than traditional serums, and therefore, offer foolproof portion control.

“Individually-packaged ampoules provide a dose-controlled amount of high quality ingredients,” says Annie Chiu, MD, an LA-based dermatologist and dermatology staff member at Cedars-Sinai Medical Center. “I find a lot of people overestimate how much they need in potent skin products like serums, which can be more costly. The skin can only absorb a certain amount of nutrients at a time, so more is not always better. Ampoules are a great way to know you are doing enough but not wasting product.”

Dr. Chiu also offers a tip for justifying some of the heavier price tags out there. “Really look at the ingredients,” she advises. “Sometimes, ampoules are just a marketing ploy and not necessarily higher concentration.”

Ahead, follow this guide to find the right ampoule for your skin type.

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