99944200907B Speed-Feed 400 Trimmer Head - Fits Echo SRM Series & Straight Shaft Trimmers (SRM-225, SRM-220, SRM-230

99944200907B Trimmer Head

Key Features

• Patented "Speed-Feed" Reloading: Engineered for maximum efficiency, this head allows you to reload the entire spool in under 30 seconds without disassembling the housing or using any tools.
• Commercial-Grade Bump Advance: Features a high-response internal spring and balanced centrifugal design for reliable, jam-free line advancement with a light tap on the ground.
• Split-Spool Internal Divider: Designed with a specialized internal wall that keeps the two line segments separate, preventing line "welding" and overlapping that causes feeding failures.
• Reinforced Alloy Eyelets: Equipped with heavy-duty metal line exits that resist friction-induced heat, ensuring the line remains flexible and doesn't snap at the head during thick brush clearing.
• Universal Straight-Shaft Balance: Specifically balanced to reduce vibration across a wide range of engine displacements, protecting your gear head bearings and reducing hand fatigue.

Replaces / Cross-Reference Part Numbers

• 99944200907B
• 99944200907
• 99944200908
• X047000800

Compatibility & Fitment

This "400" series head is the primary replacement for Echo's professional-grade straight-shaft trimmers. Key compatible models include:

• Echo SRM Entry Series: SRM-210, SRM-220, SRM-225, SRM-225i, SRM-230, SRM-231.
• Echo Professional Series: SRM-265, SRM-266, SRM-266T, SRM-280.
• Echo High-Torque & New Models: SRM-2320T, SRM-2620, SRM-2620T, SRM-3020.
• Technical Specification: Fits all straight-shaft models utilizing the M10 x 1.25 LHF (Left Hand Female) arbor thread.

When to Replace

• Worn-Through Bump Cap: The center knob has ground down from pavement contact to the point where the internal spring is visible or the line release no longer functions.
• Cracked Housing: Visible stress fractures or missing chunks of the black outer shell, which can cause the head to shatter at high RPMs.
• Eyelet Failure: The metal eyelets have fallen out or are deeply grooved, causing the trimmer line to snap off inside the head repeatedly.
• Loading Mechanism Jam: The internal indexing mechanism is seized with dried sap and debris, preventing the arrows from aligning for a reload.
• Excessive Vibration: The head has become unbalanced due to uneven wear, putting unnecessary stress on the trimmer's gear head and drive shaft.

Installation Tips

• Left-Hand Threads: Remember, this head is Left-Hand Threaded. To tighten it onto the trimmer, you must turn it Counter-Clockwise.
• Lock the Gear Head: Use a small screwdriver or the factory locking pin to hold the gear head shaft stationary while you spin the old head off and the new one on.
• Alignment for Reloading: To reload, rotate the top knob until the arrows on the knob align perfectly with the metal eyelets. Push your line through until it is even on both sides, then twist the knob to wind.
• Soak Your Line: To extend the life of your trimmer line, soak the spool in water for 24 hours. This keeps the nylon hydrated, making it more flexible and resistant to snapping at the eyelet.
• Clean the Spring: Every time you reload the line, shake out any dirt or grass trapped around the internal spring to ensure the "bump" action stays smooth and responsive.