4-Layer Tower of Track: upgraded the traditional 3-tier cat tower toy by adding new tiers! More tracks will bring more fun and challenges that will keep your cat entertained for hours! DIY Emoji Stickers: The included cat toy emoji stickers can make the toy even more special! You can choose from three matching expressions or create your own, let your imagination fly! Keeps Cats Busy: The colorful balls in this cat roller toy will move quickly along the track under the cat's impetus, attracting cats to chase and play, keeping naughty cats busy to avoid destroying the furniture! No Supervision Needed: cat ball toys are completely safe for kittens to play happily on their own when you're busy or out and about, helping to eliminate feline boredom and depression. Sturdy Construction and Non-Slip Base: The ABS resin material is more stable and can withstand the scratching and biting of naughty cats, and the wide non-slip base can keep the toy standing at all times! Perfect for one or more cats!