Replacing our current luggage supplier — 4,500 pcs/year hardshell cases, 20" & 24"

Our current supplier's wheel assemblies and zipper pulls have been failing well inside the return window, and we are moving the line to a new manufacturer. We sell hardshell suitcases direct to consumers through our own site and major US marketplaces, mainly the 20 and 24 inch sizes. What matters most this time: spinner wheel durability (we want confirmation of drop-test or cycle-test results if you have them), a branded or equivalent-grade zipper, and a polycarbonate shell rated for repeated compression in transit. TSA combination lock as standard. Volume: about 4,500 pieces per year split roughly evenly between the two sizes, ordered in smaller releases rather than one large batch so we can keep working capital down. Packaging: neutral color box is fine, we relabel in-house. Please send unit pricing at this volume, any documentation on wheel/zipper durability testing, GRS and RoHS certificates, and lead time from PO to first delivery DDP Los Angeles.