Instrument colletknob / turnknob 14.5mm black with white line.
For shaft size Ø6mm.
Used among many of the Becker devices.
Fits to all Becker AR32xx, AR42xx and AR62xx radios, swell as all BXP64xx transponders.
Also suited for the Alexander Schleicher rotary main switch.
And many more.

The turnknob cap is to be ordered separately.