There are several types of guards for gutters. "Gutter Guard" is the most well known name but is the most expensive and does the same thing as some of the others. I cant think of the name we install but its about half the price and works just as good.
From my experence with them, they work pretty good with leaves but pine straw still seems to weave its way under the guards and into the gutters. It might block out a bit of the straw but not all of it, delaying your cleanings from 1 per year to maybe every other year, but then ya have the extra step of pullin the guards off to clean out the straw.