the Shark NV255 vacuum cleaner does not have a round top filter. It typically uses a combination of foam filters and HEPA filters, but there is no round top filter specified for this model.
However, please note that product offerings and specifications can change over time, and there might be newer models or updates that I am not aware of. To find the most accurate and up-to-date information about filters and replacement parts for the Shark NV255 vacuum cleaner, I recommend visiting the official Shark website or reaching out to their customer support directly. They will be able to provide you with the correct information and direct you to authorized dealers or retailers where you can purchase genuine Shark replacement parts.