Fill in the blank: "_____ ads display one primary image with three smaller images underneath when viewed on mobile devices."

Collections ads are a specialized format designed to provide a rich, immersive shopping experience, particularly for mobile users. Structure: They consist of one large primary creative (either an image or a video) followed by a row of at least three secondary images. User Experience: When a Pinner taps on the primary asset, they are taken to a full-screen "Instant Experience" where they can browse up to 24 related products from your catalog. Mobile-First: While they can appear on desktop, the multi-image layout is specifically optimized for the mobile feed to drive higher engagement and product discovery. Use Case: This format is highly effective for retailers who want to show a lifestyle image (the "hero" shot) and simultaneously showcase the individual products that make up that scene.