Black & Decker Trimmer Line, 20-Foot, 0.065-Inch

I keep a couple of factory-wound spools on hand so I can swap and keep moving, especially during peak growing season. The RS-136 spool from Black & Decker has been my go-to for light-duty trimming and edging around beds, walkways, and fences. After running several of these through an older ST4500, here’s how it holds up in real yard work.

Design and compatibility

This is a simple, factory-wound, 0.065-inch line on a 20-foot spool designed for bump-feed heads. It’s meant for a range of legacy Black & Decker trimmers—models like the ST1000 through ST5000 series, GE600, CST800, and my ST4500. The plastic hub snaps into place securely and indexes correctly with the trimmer head. Because it’s a pre-wound cartridge, there’s no guesswork about winding direction or evenness, which is where a lot of feeding issues begin.

At 0.065 inch, the line spec makes its intent clear: light-duty trimming, not brush clearing. If your yard is mostly grass, some thin weeds, and tidy edges, this diameter is appropriate. If you regularly tackle thicker weeds, woody stems, or long, neglected growth, you’ll want a heavier trimmer and thicker line altogether.

Setup and installation

Swap-in is straightforward. Pop the cap, pull the old spool, drop this one in, feed the line through the eyelet, and reinstall the cap. The line comes off the spool cleanly thanks to the factory wind—no springy loops, no crossovers, and no “bird’s nest” surprises. I also appreciate that the line’s end is left at a sensible length so it threads through without wrestling.

One small tip: give the line a gentle tug after seating the spool to ensure it’s caught in the notch and tensioned properly. That helps the bump-feed engage right away.

Feed performance in the yard

With a fresh install, the feed on my trimmer has been consistent. A light tap on the ground releases line predictably, and the spool doesn’t overrun or dump extra line under inertia. That’s one advantage of a correctly tensioned factory wind; even small inconsistencies in manual winding can cause uneven feed or “welding” (where heated line fuses together on the spool). I haven’t had welding with this spool, even after longer trimming sessions in warm weather.

Cut quality is right where I want it for 0.065-inch nylon. It gives crisp edges along sidewalks and curbs, and it trims grass cleanly around posts and swingsets when I keep the head at a low angle and the line fresh. You won’t get the aggression of a 0.080-inch line on thick weeds, but for lawn grooming this hits the mark.

Durability and line life

Here’s where expectations matter. A 20-foot spool isn’t meant to last a whole season. For my roughly quarter-acre space, with edging, a couple of garden beds, and fence posts, I usually finish a full trim and edge on a single spool with a bit left over. If I’m cautious around hard surfaces—e.g., sweeping near chain-link rather than grinding into it—I can squeeze a session and a half.

If you habitually edge against concrete at high speed, or if you’re trimming against rough chain-link, the thin line will snap more often and you’ll burn through this spool in a single outing. That’s not a fault of this cartridge specifically; it’s the tradeoff of 0.065-inch line. Technique matters: lower RPM near hard edges, use the tip of the line rather than the mid-span, and let the tool do the work. Those adjustments noticeably extend line life.

The spool hub itself has held up to multiple installations without warping or cracking. The cap on my trimmer still locks on firmly with this cartridge, and I’ve had no cases of the spool popping loose mid-job.

Convenience vs. cost

Pre-wound spools are always a convenience play. Could you save money by buying bulk 0.065-inch line and winding your existing spool? Absolutely. You’ll also spend time making sure you’ve got the right winding direction, tension, and an even lay, and you’ll occasionally fight with memory coils that don’t feed well. If you’re trimming weekly and going through multiple spools a month, bulk line may be worth the hassle.

For occasional to moderate users, this cartridge finds a sweet spot. It costs more per foot than bulk line, but it eliminates downtime, and I value that predictability. I toss a spare in my pocket and keep cutting; no bench time, no rework.

Where it shines

• Fast, clean installs: The factory wind means drop-in and go. No snarls.
• Reliable bump-feed: Taps out line consistently without overfeeding.
• Clean cut quality for lawn work: Grass and light weeds are handled neatly.
• Secure fit: The hub seats well and stays in place during operation.

Where it falls short

• Shorter runtime per spool: 20 feet is modest. Larger properties may need a swap mid-job.
• Light-duty only: 0.065-inch line isn’t forgiving against concrete, rocks, or thick stems.
• Value for heavy users: If you burn through line weekly, bulk winding may be more economical.

Practical tips for better results

• Mind your edges: Reduce speed near concrete and brick. Use the line tip and float the guard just off the surface to minimize break-offs.
• Stagger your feed: Don’t bump every few seconds. Trim until you notice cut quality tapering, then feed a little line.
• Keep spares dry and shaded: Heat can add coil memory; storing spools in a cool, dry place helps prevent feed issues.
• Trim before you edge: Trimming first uses shorter line lengths, saving fresher line for the more abrasive edging pass.

Who it’s for

If you’ve got a compatible Black & Decker trimmer—especially an older ST-series—and your yard work revolves around routine lawn maintenance, the RS-136 spool fits right in. It’s designed for convenience and everyday trimming rather than land clearing. Homeowners in small to medium suburban lots, or anyone who values a quick swap over fiddling with a bulk spool, will appreciate it.

If your yard is larger or you tackle heavier growth regularly, you’ll either go through these quickly or discover the limits of 0.065-inch line. In that case, consider a trimmer that accepts thicker line or a larger-capacity spool, or plan on bulk winding to control cost.

Reliability and consistency

Over multiple cartridges, I’ve had consistent feeding, predictable wear, and zero surprise failures of the hub or wind. That consistency is really the story here. It’s not a flashy upgrade, but it keeps an older trimmer at peak reliability with minimal fuss—and that’s exactly what a replacement spool should do.

Final recommendation

I recommend the RS-136 spool for light-duty yard maintenance on compatible Black & Decker bump-feed trimmers. It installs quickly, feeds reliably, and cuts cleanly for routine trimming and edging. The 20-foot length and 0.065-inch diameter set clear expectations: it’s a convenient, short-session spool for grass and small weeds, not a heavy-duty option. If convenience and dependable feeding matter more to you than squeezing every penny per foot of line, this cartridge is a smart, low-friction choice. If you maintain a large property or work against abrasive surfaces frequently, be prepared to carry a spare—or look to bulk line and manual winding to control costs.