"Walter Cohen" wrote in message
The only difference that I can see (on the internet) is that they are of
varying widths (blade).


The wider the blade the (choose one)
a. faster you get done
b. the harder it is to pull.

Yes, they do work and can help prevent ice dams. We use one at work that is
about 18". I don't think I'd go too wide as it can get unwieldy.