Which of the following is categorized as an outside parcel?

An outside parcel is categorized based on specific criteria, primarily regarding its shape, size, and packaging method. Metal-strapped boxes are outlined as outside parcels because they typically represent a bulkier, more robust form of shipping that is used for larger or heavier items requiring added security during transit.

Using metal strapping enhances the parcel's integrity and ensures it can withstand the rigors of handling and transportation. This kind of packaging is necessary for items that need additional protection or are too large to fit into standard mailing categories.

Other options, while they represent valid forms of packaging, do not match the definition of outside parcels as precisely. Bubble mailers, standard boxes, and polyethylene envelopes typically fall into categories for smaller items or standard shipping methods and are used for less bulky packages. Understanding these distinctions helps in correctly categorizing packages for processing and shipping, ensuring efficient handling through postal services.