A typical fuse link is a section of wire 2-3 gauges (AWG) smaller than the conductor it is intended to protect. If the starter power lead is AWG10, install a AWG16 fuse link. If the main wire is AWG8, install a AWG14 link.
If the main circuit wire is connected to a Volkswagen, it doesn't matter since nothing can protect the vehicle wiring harness anyway.
