DUO-N INSULATOR CAP SET (New easy-grip design)
You need these caps if you ever want to use your Duo-N with only one console connected.
These caps prevent shorting of the live plug to a grounded surface which could damaged your Duo-N and your connected console. The caps are designed for a secure fit with easy removal and install.
These caps are currently available as a set. One SNES cap + One NES cap.