Oberheim XK controller- 61 keys, but very compact and light for
that size- it's only 10"deep, 3.5" high, and 38.5" long. It's from the
same period as the Matrix 6, and has the same pitch bend/mod levers- the
wheel has a thumb part that sticks straight up for a better grip than on
the conventional Moog/Yamaha style wheel. It's in exc. cond- I'm a
sax/wind synth player, and have never taken it to a gig- just used for
arranging at home. Has a bunch of neat features: 100 single patches, 100
multi patches, 3 zones, an assignable continuous controller slider, can
send a sequencer song select, start and stop commands; 2 velocity sens.
curves; transpose up or down up to 2 octaves, or by half steps; hold and
chord functions; and an arpeggiator section w/ pretty decent features- can
use internal or external clock.

[Excerpted from a forsale posting on usenet]