I have a 18 volt B&D that was cheap and doesn't weigh much but it has just 10" cut swath. A fresh battery charge doesn't last very long either. 10 - 15 minutes tops of steady cutting and it's slowing down the last few minutes to where you aren't accomplishing much. It takes several hours to recharge too and doesn't hold a fresh full battery charge long even with no use either so best use it immediately after charging. The only thing it's been useful for is when visiting cemeteries trimming up around family graves.
