www.aade.com has digital display add ons
for many radios.
go to ebay.com and do a search on
this # 1228570102 and see photos of the vfo.
like the other reply, it lets you listen on
the reomote while transmitting on the base rig
or visa versa. great for contests or even
if you need to monitor a local emergency net
while you are on the local net too.
Kenwood made a dg-5 for digital display for
this series, rare today but some pop up at
ebay and hamfests. ANother display was
the dfd-k from Henry (tempo) that takes the
signal from pin 1 and shield pin 2 on the
9 pin plug on the back of the radio.
These are rare too but can be found now and
then, some went for 65-165 $ on ebay.
73