I stockpile these in bulk.

I LOVE THIS PRODUCT. I use this daily so I keep at least 4-5 in my makeup stash at any given time. I love the brush tip that never seems to fray, the almost never-ending ink that doesn't smudge, and the easy handling for drawing both super skinny water lines and thick, dark, dramatic cat eyes.

I'm sorry the previous reviewer had so much issues. I've never had a problem with this product since I discovered it in Seoul a few years ago!
Use with an eye primer (I use Urban Decay Primer Potion in Original) and you will have NO problems with transfers, smudging, or flaking. To remove, all you'll need is a a gentle swipe with a cotton pad + eye make up remover (I use Neutrogena Oil Free Eye Make Up Remover).

I can't say enough good things about this product! Highly recommended for those who like dark pigment and a semi-soft brush tip.

I turn into a panda with this eyeliner pen!

I don't have the most steady hand so eyeliner pens are my lifesavers. In general they're very easy to use (like a ink pen) and this one from Innisfree is no exception. The brush is a bit thicker than I normally like and hence the line comes out thicker. But that is not the biggest problem... I don't know how this product can claim to be water and oil proof when I end up looking like a panda midway through the day! It completely smudged onto the area underneath my eyes so I looked like the undead. My colleagues even asked me if I was ok because my face (eyes) seemed a bit "tired". Sigh, I cannot in good conscience recommend this to anyone.