Sennheiser CI1 fP Sennheiser CI1 fP Description: The Sennheiser CI1 FP is an instrument cable with a 1/8" (3.5mm) mini connection and 1/4" phone connection. The cable adapts guitars and other instruments to freePORT series transmitters for wireless operation. Instrument cable for freePORT bodypack transmitter, 1/4" to 1/8" locking connector Get your Sennheiser CI1 fP product today