Earthing kit
This is a head earthing kit designed for use on the SL-C9.

It was supplied by Sony to solve the problem found on this model of white noise on the picture which is caused by static build up on the head drum. The guide sits over the drum and earths the central spindle.

White speckles on the screen which are not due to old tapes or head wear.
C9 under the lid Note, older SL-C9s may experience static pick up due to dry joints in the head pre-amplifier module. This is the metal can which pivots back giving access to the head drum pictured.

If your model is suffering from this earthing problems then you will need to order a kit.

See also the SL-HF950 static discharge notes