Fitment first · Trimmer · SKU B0F6MMZWQG

KST120X-06 KST2040-06 Replacement Spool

KST120X-06 KST2040-06 Replacement Spool for Kobalt 40-Volt Max KST 2040-06 KDLA 3040-03 String Trimmer, Replacement Line Trimmer Spool for Kobalt KST 120x-06…

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Compatibility checkpoint

Verify this before you buy

5 listed model matches
1 Match the machine model

Compare the model printed on your trimmer label with the fitment list below.

2 Confirm the line and spool spec

.065"

3 Check the part code

Match part B0F6MMZWQG or ASIN B0F6MMZWQG against the listing and your old part.

Listed model matches
Kobalt 40-Volt Max KST 2040-06 KDLA 3040-03 String TrimmerReplacement Line Trimmer SpoolKobalt KST 120x-060.065"20FT
Equipment brandKobalt
ReplacesB0F6MMZWQG
Spool typepre-wound spool
CategoryTrimmer
ConditionNew aftermarket replacement

Overview

Designed as a plug-and-trim aftermarket replacement, this pre-wound spool fits directly into the trimmer head without any custom winding. Factory spools eventually run out, and hand-winding bulk line can be time-consuming and prone to tangles. This replacement spool provides properly wound line that feeds smoothly from the first tap.

Key specifications

  • Pre-wound replacement trimmer spool
  • Direct-fit for listed trimmer models
  • Bump-feed compatible winding pattern

Compatibility

This spool is designed for Kobalt string trimmers as listed above. Confirm the spool part number, line diameter, and trimmer model before ordering to ensure a proper fit.

Installation notes

Disconnect the battery or unplug the trimmer. Remove the bump knob or spool cover by pressing the release tabs. Lift out the used spool, insert the new one with the line routed through the exit holes, and replace the cover. Pull the line to confirm smooth feed before starting.

Common questions

Q: Will this KST120X-06 / KST2040-06 replacement spool fit my Kobalt 40V Max KST 2040-06 and KDLA 3040-03 trimmer?

Yes, this spool is made for the Kobalt 40-Volt Max KST 2040-06 and is also compatible with the KDLA 3040-03 attachment-capable setup listed for this replacement. It also fits Kobalt KST120X-06 models that use the 0.065” line spool design, so the key thing to confirm is that your trimmer uses 0.065” line and this spool style.

Q: Does this spool come pre-wound with 0.065” line, and can I use thicker line like 0.080” in my KST120X-06?

This replacement spool is pre-wound with 20 feet of 0.065” trimmer line, which is the correct size for the compatible Kobalt models listed. I would not recommend switching to 0.080” on these spool heads, because thicker line can cause feeding problems, extra drag on the motor, and poor spool performance.

Q: What’s the correct way to install this replacement spool so it feeds properly in my Kobalt KST 2040-06?

First remove the battery, then open the trimmer head cap and take out the old spool and any debris packed inside the housing. Set the new spool in with the line routed through the eyelets, make sure the line direction matches the head’s feed path, and snap the cap back on securely; if it doesn’t feed smoothly, check that the line isn’t crossed or pinched under the spool.

Compatibility

This page lists compatible equipment gathered from the product fitment data. Always confirm the model number stamped on your machine before ordering.

Kobalt 40-Volt Max KST 2040-06 KDLA 3040-03 String TrimmerReplacement Line Trimmer SpoolKobalt KST 120x-060.065"20FT

Not sure which spool you need? See our guide: How to wind a trimmer spool or How to measure your old spool.

Before you buy — how to verify fitment

  1. Find your trimmer model number. It's usually on a label on the motor housing, battery slot, or lower shaft.
  2. Check spool compatibility. Compare the model number with the compatibility list above.
  3. Verify line gauge. Confirm the line thickness matches what your trimmer head requires by checking your manual or the old spool.
  4. Inspect the spool housing. Make sure the spool diameter, cap, spring post, and feed style match your trimmer head.

Frequently asked questions

How do I know this spool fits my trimmer?

Check your trimmer model number against the compatibility list above. Then verify the line gauge (.065, .080, .095) matches what your trimmer head requires — it's usually printed on the spool cap or in the manual.

Can I rewind a pre-wound spool?

Yes. Once the factory line runs out, you can rewind the spool with bulk trimmer line of the same gauge. Pre-wound spools just save time on the first load.

How often should I replace the spool?

Replace the spool when the line no longer feeds properly, the spring loses tension, or the spool body is cracked. Under normal weekend use, a spool lasts 2–4 refills before the housing wears out.

What gauge trimmer line should I use?

Match the gauge to your trimmer's power: .065" for light-duty electric trimmers, .080" for mid-range cordless, and .095" for gas-powered or heavy-duty models. Using too thick a line can stall the motor.

Where to buy

This part is available through Amazon with free returns on most orders. Use the fitment details above to compare your model, old part number, and physical specs before ordering.

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