ER400MP Curved String Trimmer Couple Shaft Attachment, Silver is giving landscapers more options with both MM4 4 Stroke engine & 18V x2 LXT (36V) cordless couple-shaft power heads (sold separately), & the curved string trimmer couple shaft attachment is the right accessory for use with this versatile system. It quickly attaches to the power head for easy operation. The M8 x 1.25 lh shaft arbor fits common sized trimmer heads for increased versatility, with bump & feed for increased efficiency. The curved shaft is engineered for improved balance & maneuverability.