It has two sides: one that has a stamp to MAKE. THE. WINGS. FOR. US (!!!) and another side to draw a steady, smudge-proof line that's extremely hard to mess up thanks to its thick felt tip. It's even available in three sizes so you can choose the thickness of your wings!
Promising review: "Let me start by saying this isn't my first cat-eye rodeo. I've tried the taping method, normal liquid liner, plastic winged stamping devices, stencils, all of it! So when I saw this I thought, meh, why not give it a shot. Well, this gem arrived and I immediately had to try it out, all while laughing at how terrible this would probably turn out....but to my surprise it was perfect. I HAVE NEVER IN MY LIFE BEEN ABLE TO DO A CAT-EYE IN UNDER 10 MINUTES, LET ALONE THE TWO MINUTES THIS TOOK TO DO! There were no sloppy streaks that I had to touch up or anything you would expect. Just a clean, crisp line." —LadyMeow
Get a pack of two (one for each eye) from Amazon for $12.99 (available in three sizes).
To learn more, check out "Hundreds Of People Swear By This Eyeliner Stamp For The Perfect Cat Eye".