What are collet knobs?

[WeAreAs1 at aol.com]

Hello KnobHeads,

In the USA, excellent collet knobs are available from Selco, located in 
Anaheim, CAlifornia.  These knobs are distributed by a few of the major 
suppliers (Newark, I think, maybe also Digikey?).  They are fairly expensive, 
and are hard to get in all of the colors and sizes that Selco makes, but they 
are very nice.  It is Selco brand collet knobs that are found on all of the 
old Oberheim synthesizers, from the SEM to the Xpander/Matrix 12.

Michael Bacich