How-To
How to Replace a BLACK+DECKER AF-100 Spool (Step by Step)
Swap an AF-100 auto-feed spool on LST, GH, ST and NST series trimmers in six steps, following BLACK+DECKER’s own manual — with a labelled diagram and the 5-3/8" line length to check.
Published
The AF-100 is BLACK+DECKER’s pre-wound auto-feed spool with .065” round line. Changing it takes no tools. The steps below follow the “Replacing the spool” section of the BLACK+DECKER 20V MAX LST400/LST420 instruction manual (page 10); the numbers match the diagram.
Steps
Exploded view Press “Next” to walk through the six steps.
- Remove the battery (or unplug a corded trimmer) before you touch the head.
- Squeeze the two tabs (1) on the spool cap and lift the cap (2) off the housing.
- Pull out the empty spool. Hold the spool with one hand and the housing with the other and pull it straight out. If the small lever in the base of the housing comes loose, put it back in place before fitting the new spool.
- Clean the housing. Remove grass and dirt from the housing and around the center post (4).
- Fit the new AF-100 spool (3). Unfasten the end of the line, guide it through the eyelet (5), then push the spool onto the center post and rotate it slightly until it seats. About 5-3/8” (136 mm) of line should stick out of the housing.
- Refit the cap. Line up the cap tabs with the slots (6) in the housing and push until the cap snaps into place. If the line now reaches past the trimmer’s line-cutting blade, trim it back to the blade.
Which trimmers take the AF-100
BLACK+DECKER lists the AF-100 (sold as “AFS Replacement Spool .065””) for these models:
| Series | Models |
|---|---|
| LST | LST136, LST220, LST300, LST400, LST420 |
| GH | GH400, GH500, GH600, GH610, GH900, GH912 |
| ST | ST6600, ST7000, ST7700 |
| CST | CST1000, CST1200, CST2000 |
| Other | BCSTRB922H1, MTC220, MTE912, NST1118, NST2018, NST2118 |
Your model number is on the label on the trimmer’s motor housing. The replacement cap for these heads is the RC-100.
AF-100 spools from APOROZONA
We sell AF-100-compatible pre-wound spools: AF-100 replacement spool and AF-100 AFS spool. Check the pack size and line diameter on each listing before ordering.
Winding bulk line instead
The manual allows refilling an AF-100 spool with bulk line, but only .065” round line, and warns that hand-wound spools tangle more often than factory-wound ones. If you refill: anchor a 3/4” (19 mm) fold of line in the spool’s anchoring slot, then wind neatly in layers in the direction of the arrow on the spool — no criss-crossing. Our spool winding guide covers the technique.
Other brands
Ryobi and Greenworks auto-feed heads work differently (different caps, spools and line diameters). See the Ryobi spool guide and the Greenworks spool compatibility guide.
Sources: BLACK+DECKER LST400/LST420 20V MAX Trimmer/Edger instruction manual, “Replacing the spool” and “Rewinding spool from bulk line”, p. 10 (PDF); BLACK+DECKER product page for the AFS Replacement Spool .065” 2-pack (blackanddecker.com), both checked September 25, 2026.
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