The most critical factor is the Wire Gauge (AWG); for standard passenger vehicles, 4 to 6 AWG is common, while heavy-duty trucks require 1/0 or 2/0 AWG to handle higher cranking currents. You must also verify the Conductor Material, prioritizing 100% Oxygen-Free Copper (OFC) for maximum conductivity and corrosion resistance over cheaper Copper-Clad Aluminum (CCA). Additionally, ensure the Insulation Material is made of EPDM or high-grade PVC that is rated for temperatures up to 105°C (221°F) and is resistant to oil, battery acid, and abrasion.