All of my connector pigtails are sold with OEM quality terminals and seals.  Wire used is Genuine mil-spec tefzel wire, common in aviation & motorsports, which is made of tinned copper strands.  This allows for better corrosion resistance, excellent conductivity & makes repairing/soldering much easier.  The wire has a Teflon like insulation that is extremely durable compared to standard automotive grade wire.  Most connectors sold by others do not offer these properties