It's so thin! Because it's so thin, you can't complete your eyeliner application in one go, but it's easy to hold and has a diamond cut design so the pen doesn't slip off, making it easy to apply. I tried using it as an eyeliner, and it didn't smudge or come off even when rubbed. I thought it was resistant to tears and sweat, and since the packaging says to use makeup remover, I thought it might be difficult to remove with hot water. However, I used cleansing and it came off easily. The color is jet black as the name suggests, and I'd like to use it when I want to apply strong makeup. However, it also seems to go well with pink-toned makeup.