Definition
An RCS carousel is a horizontally scrolling set of rich cards sent as one RCS Business Messaging message, so a user can compare several products, plans or options. Google's documentation allows a minimum of two and a maximum of ten cards.
Each card in a carousel follows the normal rich card rules: media, title, description and up to four suggestions. Carousels can contain only vertical rich cards. Suggestion chips can still be added below the carousel to move the conversation forward.
Google's design guidance recommends putting the best option first and making clear why. It also says chips below the carousel should not repeat options already in the cards, and should not be used to select items from the carousel.
Typical uses are mobile plans, flight or hotel options, new arrivals in retail, or a choice of delivery slots. Each card's buttons return their own postback data, so the business knows which item was chosen.
Keep card heights and image ratios consistent. Mixed heights look broken on some devices. Plan the SMS fallback separately, because a carousel cannot be converted into a single SMS without losing most of its content.