99944200903 Speed-Feed 450 Trimmer Head - Pack of 2

Key Features

• 30-Second Reload: Engineered with "Speed-Feed" technology that allows the spool to be reloaded without disassembly. Simply align the arrows, feed the line through, and twist the knob.
• High-Capacity Spool: Designed for professional use, holding more line than standard manual heads to reduce downtime on large properties.
• Heavy-Duty Bump Feed: Features a reinforced, high-impact bump knob and specialized eyelets to withstand high-RPM contact with concrete and fencing.
• Universal Compatibility: Includes a set of adapter bushings and studs to fit a wide variety of straight-shaft and curved-shaft trimmers.
• Precision Balance: Manufactured to strict tolerances to reduce vibration, extending the life of the trimmer's gear head and reducing operator fatigue.

Replaces / Cross-Reference Part Numbers

• 99944200903
• X047000940
• X047000941
• 99944200902
• X047000580
• 78890-21001 (Shindaiwa)

Compatibility & Fitment

This trimmer head is a standard upgrade for Echo and Shindaiwa professional units. Key compatible models include:

• Echo SRM Series: SRM-266, SRM-266S, SRM-266T, SRM-266U, SRM-280, SRM-280S, SRM-280T.
• Echo High-Torque: SRM-2620, SRM-2620T, SRM-3020, SRM-3020T.
• Shindaiwa: T230, T231, T242, T2510, T260, T261, T270, T272, T282, T344.
• Other Brands: Fits select Stihl, Husqvarna, Maruyama, and RedMax straight-shaft trimmers using the included adapter kit.

When to Replace

• Worn-Through Bump Knob: The plastic on the bottom knob has worn down to the spring or internal metal, preventing the line from advancing.
• Grooved Eyelets: The metal eyelets (where the line exits) have developed deep notches, causing the trimmer line to break off inside the head.
• Stuck Mechanism: The internal ratcheting gear is stripped or melted due to line friction, making it impossible to reload.
• Excessive Vibration: The head is physically cracked or missing a piece, creating an imbalance that can damage the trimmer's driveshaft.

Installation & Loading Tips

• Left-Hand Threads: Most straight-shaft trimmers (like the SRM-266) use a counter-clockwise tightening direction. Spin the old head clockwise to remove it.
• Align the Arrows: To load, rotate the top knob until the arrows on the side of the knob line up with the eyelets.
• The 10-Foot Rule: Insert approximately 10–12 feet of .095" line through one eyelet and out the other. Pull it through until the lengths are even on both sides.
• Winding: Hold the trimmer head and twist the bottom disc (or knob) to pull the line into the spool. Do not wind it manually by opening the head unless there is a tangle.
• Recommended Line: For best results on Echo 266/280 models, use .095" or .105" professional round or square line.