Here are some pics that we use in the marine market. Until Centa came
along most marine transmissions sounded like there was a gremlin in the
gear box with a ball peen hammer trying to get out. We us these behind a
diesel from idle up to about 1800 rpm's. Now the same combo can idle
down to 400rpm and still no hammer packin' gremlin. Centa has made these
with different bolt up hole patterns and different ID drives like keyed
and splined. In the marine market they seem to last 3000 to 5000 hours
with big reduction ratio's and large dia. propellers. The left pic. fits
a 230hp diesel @ 2500 RPM and the right fits a 60hp diesel up to 3000
rpm.  Centa has been a great company to work with, just give them a
call.

Tom/norpro

Tom,
Their good for the negative torque responses, but their RPM limited, in fact
the bigger they are the less RPM their rated for. Probably gyroscopic forces
at work on the synthetic compound.
George ( down under)