They're fiber reinforced resin and very light. IIRC, I weighed a set at 26gm complete. I'm not aware of breakage issues; the Simplex Delrin levers with that problem lacked the fiber reinforcement. Otherwise, they're simple friction levers with performance as expected, perhaps a little more flexible than aluminum levers but how hard do you really crank on shift levers? The hardware is completely interchangeable with Campagnolo friction levers and clones such as Zeus, etc.