In my experience, the Corona Clipper GS 6750 Grass Shear is an over-rated, work making tool.  Tools should save work, not add work onto the job.  It seems to me that these clippers require more energy than they are worth.  As another reviewer said, they tend to get material stuck between the blades, perhaps requiring a strong spring to make the tool spring open, so that the jamming does not occur as often.  So, any grassy material that requires energy to cut is added to the energy-taking spring back pressure.