SRM-225 String Trimmer Head - Fits Echo SRM-225, SRM-210, SRM-2100, SRM-200

SRM-225 String Trimmer Head

Key Features

• Lightning-Fast Reloading: The patented Speed-Feed 400 design allows you to reload the trimmer line in under 30 seconds without disassembling the head; simply line up the arrows, feed the line through, and twist the knob.
• High-Capacity Spool: Designed to hold a significant amount of 0.080" or 0.095" diameter line, reducing downtime and keeping you in the yard longer between refills.
• Smooth Bump-Feed Advance: Features a precision-balanced internal mechanism that provides reliable line advancement with a light tap on the ground, minimizing line welding and jams.
• Heavy-Duty Construction: Manufactured from high-impact, glass-reinforced nylon to withstand the rigors of commercial landscaping and high-velocity contact with hard obstacles.
• Low-Vibration Operation: The factory-balanced design reduces engine and shaft vibration, leading to less operator fatigue and a longer lifespan for your trimmer's gear head.

Replaces / Cross-Reference Part Numbers

• 99944200907
• 99944200908

Compatibility & Fitment

This "400" series head is the standard replacement for most Echo and Shindaiwa straight-shaft trimmers. Key compatible models include:

• Echo SRM Series: SRM-225, SRM-225i, SRM-210, SRM-2100, SRM-200, SRM-230, SRM-250, SRM-265, SRM-266.
• Shindaiwa T-Series: T195S, T220, T222, T230, T231, T242, T242X.
• Technical Fitment: Designed for straight-shaft trimmers 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 it no longer functions or the internal spring is exposed.
• Cracked Outer Shell: Visible fractures in the black housing which can cause the head to shatter or become dangerously unbalanced at high RPMs.
• Loading Mechanism Failure: The internal eyelets no longer align with the arrows, or the twisting mechanism has become stripped or seized with debris.
• Missing Eyelets: The metal line exits have fallen out or are deeply grooved, causing the trimmer line to snap off inside the head constantly.
• Excessive Vibration: The head has become structurally unsound or unevenly worn, putting undue stress on the gear head and engine.

Installation Tips

• Left-Hand Threads: This head is Left-Hand Threaded. To install, turn the head Counter-Clockwise onto the gear head shaft.
• Lock the Shaft: Insert a small screwdriver or the factory locking pin into the gear head hole to hold the shaft stationary while you spin the old head off and the new one on.
• The Loading Arrow: To reload, rotate the top knob until the arrows on the knob align perfectly with the metal eyelets. Push your line straight through the head until it is even on both sides, then twist the knob to wind.
• Line Choice: For the SRM-225, 0.095" line provides the best balance of durability and cutting power without over-stressing the engine.
• Soak Your Line: Professional tip: keep your spare trimmer line in a bucket of water. Hydrated nylon is much more flexible and significantly less likely to snap at the eyelet during heavy use.