Stihl 4112 713 4100 25.4 mm/ 1" Brush Knife Steel Blade

What It Is

This is a genuine Stihl brush knife blade (25.4 mm/1" center hole) designed for heavy-duty clearing of thick weeds, brush, and saplings on string trimmers and brushcutters. It replaces worn or damaged blades on compatible Stihl and select other straight-shaft trimmers.

Fitment & Compatibility

• Center hole: 25.4 mm (1 inch) – measure your existing blade’s center hole; this only fits shafts with that exact diameter.
• Model check: Fits Stihl FS 55, FS 70, FS 80, FS 90, FS 100, FS 110, FS 130, FS 200, FS 250, FS 350, FS 400, FS 450, FS 500, and KM 90, KM 100, KM 110, KM 130 combisystems. Not compatible with smaller consumer trimmers (e.g., FS 38) that use a 20 mm hole.
• OEM vs aftermarket: This is genuine Stihl (part #4112 713 4100). Aftermarket blades are cheaper but may lack same hardness or balance. Verify your model’s support washer/retaining nut (some require an adapter for 25.4 mm blades).
• Deck/size: Not for mower decks – this is a trimmer/brushcutter attachment. Blade diameter is ~8 inches; ensure your trimmer guard is rated for brush blades (usually indicated by a “grass/brush” symbol).

Key Things to Know

• Installation difficulty: Easy if you have a blade nut tool and torque wrench. Use Stihl’s recommended torque (typically 25–30 Nm). Over-tightening can strip the shaft.
• Sharpening: Can be resharpened with a file or grinder, but the blade is hardened – expect slower sharpening than steel mower blades. Replace if bent or chipped.
• Safety: Requires a brushcutter guard with a deflector bar. Never use on a trimmer without a brush blade-rated guard – blade can throw debris at high speed.
• Performance: Cuts thick brush efficiently but dulls faster in sandy/dirty conditions. Keep clean for best life.

Should You Buy It

If you own a compatible Stihl straight-shaft trimmer/brushcutter and regularly tackle heavy weeds, briars, or saplings, this genuine blade is a reliable upgrade. It’s pricier than aftermarket options but offers consistent balance and durability. Skip it if you only cut grass or have a smaller consumer model with a 20 mm hole.