A customer asks about a flat-rate shipping option, saying they want a predictable price regardless of weight (within the box's limit). What is the BEST response?

Knowledge of common USPS services helps a retail associate serve customers well. Priority Mail Flat Rate allows shipping items in a designated flat-rate box or envelope for one set price regardless of weight (up to the box's limit and within domestic rules), which suits customers who want predictable pricing for dense items. The best response explains this option accurately and helps the customer pick the right box size. Denying the service exists, refusing to help, or ignoring the flat-rate request all give poor service. (Exact prices and box dimensions are confirmed at the counter, since they change over time.)