Branded USB drives are an effective promotional product as they provide functionality while spreading brand awareness. There are several customization options for USB drives, including full-color printing, laser engraving, screen printing, and embossing. Accessories like key rings, lanyards, and magnetic packaging boxes can be added. When choosing the capacity for a promotional USB drive to hand out at events, a 1GB drive is recommended over smaller 64MB drives, as it can store meaningful amounts of data and ensure the drive remains useful.