It’s a sticker that story posters can put on photos or videos, and allows their followers to answer questions using an emoji that slides along a scale.
To add an emoji slider sticker to your story, select it from the sticker tray after taking a photo or video. Place it anywhere you’d like and write out your question. Then, set the emoji that best matches your question’s mood. You can pick from a few of the most popular emoji, or choose almost any emoji from your library if you have something specific in mind. Like with the poll sticker, friends and followers will be able to respond to your slider as soon as you’ve shared it.