OEM N508388 string trimmer replacement spool & string DCST991M1 DCST920B

What It Is

This is an OEM replacement spool and pre-wound string for DeWalt cordless string trimmers. It holds 0.080-inch line and is designed for heavy-duty trimming in residential and commercial yards.

Fitment & Compatibility

• Exact models: Fits DeWalt DCST991M1 and DCST920B trimmers only. Do not use on other DeWalt or generic trimmer models without verifying the spool housing.
• Measurements: Spool diameter is 3.5 inches; line length is 20 feet. Compare to your existing spool—if dimensions match, it’s compatible.
• OEM vs aftermarket: This is genuine DeWalt OEM. Aftermarket spools (e.g., Oregon, Rotary) may fit but often require trimming the line or modifying the housing. OEM guarantees no fitment issues.
• Check before buying: Remove your current spool and confirm the model number on the trimmer head (usually stamped on the housing). Also verify your trimmer’s line diameter spec—0.080-inch is standard for these models.

Key Things to Do

• Installation is tool-free—just depress the spool retainer tabs and pop the old spool out. No disassembly of the trimmer head is needed.
• Line is pre-wound and pre-cut to the correct length. You won’t need to measure or wind it yourself, saving about 5–10 minutes per replacement.
• Line durability is good for normal grass and light weeds but will snap faster on thick brush or against rocks. For heavy-duty use, consider a thicker line (0.095-inch) in a compatible aftermarket spool.
• Common gotcha: The spool can be hard to seat if the line isn’t fully seated in the housing groove. Ensure the line is snug before pushing the spool down.

Should You Buy It

Buy this if you own a DCST991M1 or DCST920B and want a hassle-free, guaranteed-fit replacement that avoids the guesswork of aftermarket options. It’s ideal for routine maintenance or if you’re new to string trimmer repairs. If you’re on a tight budget or trim thick brush regularly, a cheaper aftermarket spool with thicker line may be a better value.