Certified Filter Service, an importer specializing in industrial air‑filter equipment, relies almost exclusively on a single Chinese supplier, GZ Guanli EFE Co Ltd, with monthly shipments that average 1–2 containers (≈1.5 TEU) and 4 000‑15 000 kg per load, consistently using HS Code 842420 (air‑filter machines) and occasional 842410/842430 codes. Dispatches originate from the Yantian (and occasionally Shekou) ports and are routed to major West Coast gateways—Los Angeles and Long Beach—providing a predictable coast‑to‑coast supply chain. For suppliers, this pattern signals a high‑volume, repeat buyer with stable demand and a willingness to engage a sole source, suggesting strong purchasing power and reliable payment history. For customs brokers, the uniform HS‑code usage, regular loading ports, and fixed discharge points facilitate streamlined documentation, low variance in tariff classification, and efficient clearance timelines, reducing inspection risk and enabling proactive compliance planning.