These are the Parsons Products Safety Plug Clips for JR Wires.  The Parsons Products Safety Plug Clips provide inexpensive insurance against radio failure. The bright yellow plastic clips simply clamp on to servo plugs to prevent separation, perfect for use with Y-harnesses, aileron extensions, battery to switch harness connections and many more uses. Its unique design allows modelers to quickly plug/unplug the connection yet maintains a secure grip on both plugs once fastened.  There are 3 safety clips per packages.