Name: 4Pack 537338701 Trimmer Head Bump Knob
Brand: APOROZONA
SKU: B0F43XMLFS

4Pack 537338701 Trimmer Head Bump Knob

4Pack 537338701 Trimmer Head Bump Knob for Husqvarna 124L 125L 128L 128LD 128LDx 128R 223L 223R 322C 323C 325C 326Cx String Trimmer

Amazon price when checked $14

Amazon rating 2.2 / 5

Check price

Compatibility checkpoint

Verify this before you buy

Check the current listing

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

trimmer head

3 Check the part code

Match SKU B0F43XMLFS or ASIN B0F43XMLFS against the listing and your old part.

Equipment brandHusqvarna

Pack4-pack

Spool typetrimmer head

CategoryTrimmer

ConditionNew aftermarket replacement

What the listing states

Listed as compatible with: Husqvarna 124L 125L 128L 128LD 128LDx 128R 223L 223R 322C 323C 325C 326Cx String Trimmer

From our Amazon listing, checked September 25, 2026. Model and part-number matches are the seller's; confirm against the part on your machine.

Before you buy — how to verify fitment

Find your trimmer model number. It's usually on a label on the motor housing, battery slot, or lower shaft.
Check spool compatibility. Compare the model number with the compatibility list above.
Verify line gauge. Confirm the line thickness matches what your trimmer head requires by checking your manual or the old spool.
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 sold and shipped through Amazon; return options are shown on the listing. Use the fitment details above to compare your model, old part number, and physical specs before ordering.

Affiliate disclosure: we may earn a commission when you purchase through this link, at no extra cost to you.