Sta-Kon RC717M INS VIN RNG TRM 12-10 1/4 YEL MYLAR

The RC717M is sized for 12-10 AWG stranded or solid copper wire. The yellow insulation is the standard color code for that gauge range, so on a panel where blue is 16-14 and red is 22-18, yellow tells you at a glance it's the 12-10 barrel. Anything smaller than 12 AWG won't hold a reliable crimp in this barrel; step down to a blue 16-14 terminal for that.

The barrel is copper, which is what you want for copper building wire and appliance cord. It is not rated here for aluminum conductors, so do not use it to terminate aluminum feeders; that calls for an AL/CU listed connector instead.

The RC717M uses a vinyl insulating sleeve with a Mylar liner inside the barrel entrance. That liner stiffens the insulation so the sleeve does not split or mushroom when the crimp die closes, and it keeps the conductor strands from pushing through the back of the insulation. It's the detail that separates a nylon or Mylar-lined vinyl terminal from a bare vinyl one on repetitive panel work.

Crimp it with an insulated-terminal crimper set to the yellow 12-10 AWG nest. The die position is color coded on most trade crimpers, so the yellow sleeve on the RC717M tells you which jaw to use. A yellow-nest crimp on a blue or red die will under-form the barrel and leave a pull-out failure waiting on the job.

Yes. The RC717M vinyl insulated ring terminal has a country of origin of the United States, which matters on government, school, and transit jobs carrying domestic-content requirements.