If you hear the phrase “eyebrow extensions” and immediately picture something along the lines of impossibly long eyelash extensions, just glued on a bit further north, well, don’t. Long, flowing eyebrows remain firmly not a thing. Instead, brow extensions fill in gaps and enhance eyebrow shapes.

But do you really need eyebrow extensions? How do they work? And how long do eyebrow extensions last? Below, with the help of a co-owner of Occhi Lashes outside Chicago, we outlined the basics of this trending service so you know what to expect before you hang up your tweezers for good.

Why should you try them?

You can thank celebs like Kim Kardashian, Cara Delevingne, and Angelina Jolie for bringing the fuller brow look back. But you don’t have to be a celebrity (or want to look like one) in order to benefit from brow extensions.

The main thing they can do? Tweak your brow shape. Your natural eyebrow shape is just a starting point. Extensions can give you a higher arch, a longer tail, more or less curve—you name it. (Don’t worry: stylists hold stencils up to your face to help you translate your mental picture into a concrete plan.)

They’re also great for filling in bare spots. Because of this, brow extensions are a great option for people who have overtweezed, those with age-related brow loss, or those with medical-related brow loss caused by chemotherapy, radiation, or trichotillomania.

How do eyebrow extensions work?

Turns out getting perfect eyebrows is actually pretty quick and painless, with appointments rarely going beyond 30–45 minutes. First, the technician will clean and prep the brows, and though it may be counterproductive, don’t be surprised if they also pluck away any stray hairs falling outside the brow line. This is all part of establishing the perfect eyebrow shape.

Next, the technician will likely draw or stencil on an outline of your new brow shape. Don’t be alarmed if this line looks cartoonish as it’s merely a guide, and the technician will know how to place the brows to make the look seem as natural as possible. Next, he or she will use a surgical-grade adhesive to affix the extensions, one-by-one to the natural brow hairs or directly to the skin, depending on your needs.

Keep in mind, your finished brows won’t look perfectly symmetrical. But this is a good thing, since natural brows aren’t perfect either and a little asymmetry will help make them more genuine.

How long do eyebrow extensions last?

The answer to this question largely depends on the type of extensions you get and your daily habits. Extensions applied directly to the natural brow hairs will fall out naturally with the hair’s shedding cycle, typically anywhere from 6 to 16 days. Of course, if you’re the type of person who routinely rubs their eyes or touches their face, don’t be surprised if they fall out quicker.

Extensions applied to the skin fall out even quicker. This is because technicians usually use a gentler, less durable glue when applying directly to the skin, so as to avoid breakouts and allergic reactions. For this reason, extensions affixed to the skin may be better suited for special occasions than everyday wear.