Oregon 55-265 Trimmer Head Speed Feed Straight, 4-1/2" 4-1/2" Left-hand Spool Adaptors included: 7mm x 1.0 Left-hand, 8mm x 1.25 Left-hand, 10mm x 1.25 Left-hand Easy load in 30 seconds or less Semi-matic head for medium to heavy duty applications Inner wall reduces debris inside the head and large durable eyelets increase line life Line tensioning system with split spool reduces vibration