Sterling Pacific machines their 40-liter cabin travel cases from reinforced 5000 series aluminum shaped under hydraulic pressure from 0.9mm sheets, then reinforced at load points with 1.5mm 5052 aluminum corners. Over a hundred SAE 304 stainless steel rivets rated to 26,000 psi shear strength hold the frame together. Italian full-grain leather wraps the top and side handles, developing patina instead of wearing out. Dual thru-axle wheels recess into A380 aluminum housings to absorb impact forces that destroy plastic luggage after a dozen trips. The retractable trolley slides into a die-cast A380 aluminum housing rather than the injection-molded plastic competitors use. TSA-approved double combination locks secure the ring-spun twill interior. Lifetime warranty backed by a repair shop in Reno where every case carries an engraved batch identification number. Comes with leather care wax and aluminum pen.