Our Cat Toys have Scent Enrichment included at NO EXTRA CHARGE! Every color, every wall thickness, all of them! It’s located inside the inner ball. Please see the picture. We’ve cut a large viewing hole so you can see the interior (normally, it’s not there). All you have to do is unscrew the metal plug and pull the removeable basket strainer out with an unbent paperclip. Put whatever scent you want into it (meat, cotton balls soaked in whatever, etc.) and put it back into place with the plug. Surprise! You’ve just extended their attention time. Nothing better than a happy kitty embraced in white diamonds.