HSN Code 9704 refers to "Postage or revenue stamps, stamp-postmarks, first-day covers, postal stationery, stamped paper and the like, used, or if unused, not of current or new issue in which they have, or will have, a recognised face value." This classification code is essential for identifying philatelic items and related postal products for import/export purposes based on their nature, condition, and intended use. Common products under HSN Code 9704 include used postage stamps, first-day covers, revenue stamps, and postal stationery. Additionally, the GST rate for these items under this code ensures accurate trade compliance.