Echo Trimmer Head 99944200903 - for SRM-266, SRM-266S, SRM-266T, SRM-266U, SRM-280, SRM-280S, SRM-280T
Speed-Feed 450 trimmer head with pre-loaded orange cutting line for Echo SRM series trimmers.
Infographic showing dimensions and specifications for the Speed-Feed 450 trimmer head replacement.
Compatibility chart for Speed-Feed 450 trimmer head showing Echo SRM series fitment and serial numbers.
Exploded view of the Speed-Feed 450 trimmer head internal components showing the housing, spool, and spring assembly.
Close-up of Speed-Feed 450 trimmer head showing ABS plastic housing, metal eyelets, and durable cutting line.
Speed-Feed 450 trimmer head replacement kit for Echo string trimmers shown with troubleshooting symptoms graphic.
99944200903 Speed-Feed 450 trimmer head shown in a lifestyle graphic for efficient lawn trimming.
Installation guide for Speed-Feed 450 trimmer head showing steps to attach to Echo trimmer shaft.
Maintenance tips infographic for Speed-Feed 450 trimmer head featuring cleaning and inspection instructions.
Speed-Feed 450 trimmer head with pre-loaded orange cutting line for Echo SRM series trimmers.
Infographic showing dimensions and specifications for the Speed-Feed 450 trimmer head replacement.
Compatibility chart for Speed-Feed 450 trimmer head showing Echo SRM series fitment and serial numbers.
Exploded view of the Speed-Feed 450 trimmer head internal components showing the housing, spool, and spring assembly.
Close-up of Speed-Feed 450 trimmer head showing ABS plastic housing, metal eyelets, and durable cutting line.
Speed-Feed 450 trimmer head replacement kit for Echo string trimmers shown with troubleshooting symptoms graphic.
99944200903 Speed-Feed 450 trimmer head shown in a lifestyle graphic for efficient lawn trimming.
Installation guide for Speed-Feed 450 trimmer head showing steps to attach to Echo trimmer shaft.
Maintenance tips infographic for Speed-Feed 450 trimmer head featuring cleaning and inspection instructions.
Lifetime Warranty

Echo Trimmer Head 99944200903 - for SRM-266, SRM-266S, SRM-266T, SRM-266U, SRM-280, SRM-280S, SRM-280T

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99944200903 Speed-Feed 450 Trimmer Head

Key Features

  • Features a rapid-loading system for trimmer line refills.
  • Bump-feed mechanism advances line with a simple tap on the ground.
  • Holds up to 20 ft. of 0.095 in. diameter trimmer line.
  • Constructed with a durable, high-impact housing.

Replaces / Cross-Reference Part Numbers

  • 99944200903
  • X047000940
  • 28820-08000
  • 78890-21001
  • 385-288

Compatibility & Fitment

  • Fits various ECHO straight-shaft grass trimmers and brushcutters.
  • Commonly used on models such as the ECHO SRM266.
  • Requires a 10 mm x 1.25 mm left-hand (LH) threaded arbor for installation.

When to Replace

  • The outer housing is cracked, broken, or excessively worn.
  • The bump knob fails to advance the trimmer line upon tapping.
  • Internal components are worn and can no longer grip or feed the line properly.
  • Line eyelets are damaged, causing the line to fray or break frequently.

Installation Tips

  • Disconnect the spark plug before beginning installation for safety.
  • Lock the gearbox to prevent the head from rotating during removal.
  • Unscrew the old head by turning it clockwise (it is reverse-threaded).
  • Secure the new head by threading it on counter-clockwise until snug.
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  • FIX TRIMMER'S SYMPTOMS

    FIX TRIMMER'S SYMPTOMS

    Stuck/Tangled/ Broken trimmer head, The trimmer does not spin, The threads are stripping, Uneven Trimming, Excessive Vibration
  • SAVING SOLUTION

    SAVING SOLUTION

    Enjoy the great feeling when your trimmer is repaired and works like before - BlueStars brings DIY solutions to help you deal with any trouble
  • MAINTENANCE TIPS

    MAINTENANCE TIPS

    Regular Cleaning. Inspect the Trimmer Line & Keep surplus trimmer line around. Check the Air Filter & Fuel/Oil. Store Trimmer Appropriately
  • IMPORTANT NOTE

    IMPORTANT NOTE

    This is a replacement part designed to be compatible with certain appliances. Any brand names mentioned are used solely to indicate compatibility
EASY INSTALLATION

EASY INSTALLATION

1. Bump the bottom of the trimmer head against the ground; 2. Align arrows on top of the knob with openings in eyelets; 3. Push the line an equal distance of about 5in (13 cm); 4. Turning the top disc until tight. Test running for 5 mins to ensure proper operation.
Brand Model Number
Replace part number Echo string trimmer 99944200903, X047000940, Shindaiwa string trimmer 28820-08000, 78890-21001 X047000580, 55-265, 385-288
Echo SRM-266 S/N: T41913001001 - T41913999999 ; T42011001001 - T42011999999 SRM-266 S/N: T42112001001 - T42112999999; T42211001001 - T42211999999 SRM-266S S/N: T42312001001 - T42312999999; T43313001001 - T43313999999 SRM-266S (T42211001001-T42211999999) Steel Drive Shaft Trimmer SRM-266S (T42312001001-T42312999999) Steel Drive Shaft Trimmer SRM-266S (T43313001001-T43313999999) Steel Drive Shaft Trimmer
Echo SRM-266U 25.4cc Straight Shaft Trimmer/Brushcutter, SRM-266U (T42712001001 - T42712999999) Straight Shaft Trimmer/Brushcutter, SRM-266U (T43513001001-T43513999999) Straight Shaft Trimmer/Brushcutter SRM-266T S/N: T42411001001-T42411999999 SRM-266T S/N: T42512001001-T42512999999, SRM-266T S/N: T43413001001 - T43413999999, SRM-266T (T42411001001-T42411999999) High Torque Trimmer, SRM-266T (T42512001001-T42512999999) High Torque Trimmer, SRM-266T (T43413001001-T43413999999) High Torque Trimmer
Echo SRM-266U S/N: T42712001001 - T42712999999, SRM-266U S/N: T43513001001 - T43513999999, SRM-280 S/N: S66511001001 - S66511999999, SRM-280 S/N: S74012001001 - S74012999999, SRM-280 S/N: S81513001001 - S81513999999, SRM-280S S/N: S66611001001 - S66611999999, SRM-280S S/N: S74112001001 - S74112999999
Echo SRM-280T S/N: S66711001001 - S66711999999, SRM-280T S/N: S74212001001 - S74212999999 SRM-280T S/N: S81713001001 - S81713999999, SRM-280U S/N: S67511001001 - S67511999999, SRM-280U S/N: S75012001001 - S75012999999, SRM-280U S/N: S82513001001 - S82513999999

FAQ

This trimmer head is compatible with Echo straight-shaft trimmer models SRM-266, SRM-266S, SRM-266T, SRM-266U, SRM-280, SRM-280S, and SRM-280T. Some listings also reference SRM-280U, but if your unit is not one of the models printed in the product title, verify the original head part number on your machine before ordering.
This part is associated with part number 99944200903 and replaces X047000940. Matching either of these numbers to your original trimmer head is a good way to confirm fit.
Typical symptoms include the line not advancing correctly when bumped, frequent line jams, a cracked or badly worn housing, excessive vibration, or a spool that no longer locks or feeds smoothly. If the head has impact damage from edging, rocks, or hard surfaces, replacement is often easier than rebuilding a severely worn unit.
Installation is usually straightforward on compatible Echo straight-shaft trimmers. In most cases, you lock the gearbox or shaft, remove the old head, and thread the new head on. Plan on about 10 to 20 minutes. The exact tool needed can vary by trimmer, but commonly includes the shaft-locking pin or stop tool and a basic wrench or socket for removing the old attachment.
Before installation, inspect the output shaft threads, thrust washer, retaining hardware, and gearbox area for damage or wear. Clean away packed grass and debris from the head mounting area. If your old head failed because of vibration or impact, also check that the shaft is not bent and that the guard and gearbox are secure.
The most common causes are normal wear from ground contact, impact with concrete or rocks, heat buildup from running oversized or incorrect line, and debris working into the spool mechanism. Over-tightening during installation or continued use after the housing cracks can also shorten the life of the head.