Understanding Grass Trimmer Line and Mowing Heads

When replacing your grass trimmer line, the best choice depends on the work at hand. As a rule, the longer and denser the grass, the thicker the trimmer line should be. Thicker line demands more power, so ensure your trimmer is suited to the task.

STIHL offers a variety of grass trimmer heads compatible with domestic and professional trimmers, allowing you to adapt your tool for different jobs.

STIHL provides three main types of mowing heads that use trimmer line — each designed with a different line feed mechanism.

TrimCut Mowing Heads

With TrimCut heads, you must manually wind out the line. When it shortens, switch off the trimmer and extend the line by hand.

TrimCut C 32-2 Mowing Head

Two-line mowing head for trimming around obstacles.

£25.58

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AutoCut Mowing Heads

AutoCut heads extend line automatically when tapped against the ground while running. Centrifugal force adjusts the line length for consistent cutting.

AutoCut 36-2 Mowing Head

Practical two-line mowing head for brushcutters.

£15.22

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AutoCut C 3-2 Mowing Head

Easy to feed line during operation.

£8.50

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AutoCut C 6-2 Mowing Head

Two-line head with convenient bump feed system.

£22.69

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AutoCut C 26-2 Mowing Head

Reliable, high-performance two-line mowing head.

£36.38

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SuperCut Mowing Heads

SuperCut heads automatically extend trimmer line as needed using internal weights — ideal for effortless cutting in domestic applications.

AutoCut 27-2 Mowing Head

Two-line mowing head with automatic adjustment.

£33.16

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STIHL Tip: Prefer pre-cut line? Try DuroCut mowing heads, which use ready-cut DuroCut line with a flexible core and tough outer layer for denser vegetation.

There are three main methods for replacing trimmer line, depending on the model type.

• Standard heads: Remove and open the head to wind line around the spool manually. Follow the arrows for direction.
• Comfort heads (marked “C”): Feed line through the head and twist the base to wind internally—no disassembly needed.
• Pre-wound option: Open the mowing head and insert a ready-loaded spool.

If you’re unsure, your local STIHL dealer can demonstrate how to replace the trimmer line correctly.

STIHL produces various trimmer line profiles and thicknesses to match different materials and workloads. Round, quiet lines are standard, providing clean cuts with reduced noise.

Colour coding makes it easy to identify line thickness — for example, red line = 2.7mm diameter.

Before use, soak trimmer line in water for 24 hours to maintain elasticity. Nylon line dries out over time and becomes brittle; hydrating it restores flexibility and durability.

You can keep line stored on the reel submerged in water between uses to ensure it remains ready for your next job.

Gustharts provide advice, servicing, and demonstrations of compatible mowing heads and line types. Visit our showroom in Northumberland for help choosing or replacing trimmer line and accessories.

• STIHL offers a wide range of mowing heads and trimmer lines for every application.
• Replace line by winding manually, using the comfort twist method, or fitting a pre-wound reel.
• Soak line in water for 24 hours before use to keep it flexible.
• Always check compatibility with your STIHL trimmer model.
• For professional advice, contact your nearest STIHL dealer.