Twin Lead Ignition Coil 6V. (Generic Images Used 6V supplied) The HT Leads are 23-1/2(590mm) long. Mounting bolts are 3-9/16(90mm) apart centre to centre. Black lead : Negative Yellow lead : Positive Primary resistance :1.09ohms Secondary resistance :13-14ohms. The twin lead coils are designed for use with self-generating ignition or electronic types I would recommend fitting two separate coils to twin points system