Brian,
Polyurethane bushings, performance wise is
better than rubber.It dont flex so you have a
positive twist on your bars when making a sharp
turn.The only draw back is that over time it
makes a squeeking noise.Just keep it lubricated.
I use to have it in my Beemer and I squirt some
teflon grease on it, I would say once every 6 mo.

Clauser1