Bob,
I've used some hand guards & I think they were Bark busters Blizzard They are made of what appears to be heavy nylon & so are more flexible than the plastic ones. I find they work very well as they really reduce the wind chill factor, as that is the killer on a bike. I tried heated grips prior to this but was unimpressed as once you get a move on they don't seem to work, & the back of your hand takes all the wind anyhow. Now I fit the hand guards for winter & bring out the Gerbing gloves when it is is very cold, as Geoff says they work well. The guards are the cheapest most effective thing i've found so far.