STIHL 26RS 81 OEM 20" Chainsaw Chain – 3639-005-0081

Genuine STIHL 26RS 81 chainsaw chain, OEM part 3639-005-0081, designed for compatible STIHL Farm Boss®, Wood Boss®, and professional mid-range chainsaws.

This factory-original STIHL Rapid Super 26RS full-chisel chain is built for a 20-inch guide bar using .325" pitch, .063" gauge, and 81 drive links.

This is a genuine STIHL OEM chain — not an aftermarket replacement — sold by P&P Small Engines.

If you're looking for a STIHL 26RS 81 chain, STIHL 20-inch chainsaw chain, or STIHL 3639-005-0081, this is the OEM chain configuration to compare with your existing bar and chain specifications.

Product Overview

• Brand: STIHL
• Genuine OEM Part: Yes
• STIHL Part Number: 3639-005-0081
• Stock Number: 36390050081
• Chain Model: 26RS
• Chain Family: Rapid Super
• Bar Length: 20 inch
• Pitch: .325"
• Gauge: .063" / 1.6 mm
• Drive Links: 81
• Cutter Type: Full chisel
• Condition: New OEM
• Recommended Use: Firewood cutting, property maintenance, landowner use, and professional cutting

STIHL 26RS 81 Rapid Super Chain

The STIHL 26RS 81 is part of STIHL's Rapid Super chain family.

Rapid Super uses a full-chisel cutter profile designed for fast, aggressive cutting in clean wood. It is well suited to experienced users who want high cutting speed and strong performance from compatible STIHL saws.

The 81 identifies the 81-drive-link configuration of this specific chain loop.

For correct fitment, your saw and guide bar must match all of the required chain specifications.

Verify Fitment Before Ordering

Before purchasing, check the specifications stamped on your guide bar or current chain.

This chain requires:

• Bar Length: 20"
• Pitch: .325"
• Gauge: .063"
• Drive Links: 81

All four specifications must match your actual saw and guide-bar setup.

A chainsaw model may be available with more than one bar and chain configuration, so model number alone does not guarantee fitment.

If you're unsure, contact P&P Small Engines before ordering and we'll help verify the correct chain.

Compatible STIHL Models

STIHL 3639-005-0081 may be used with compatible configurations of:

• STIHL MS 260 Pro
• STIHL MS 261
• STIHL MS 270
• STIHL MS 271 Farm Boss®
• STIHL MS 290 Farm Boss®
• STIHL MS 291 Farm Boss®
• STIHL MS 310

Important: Your saw must be equipped with a compatible 20-inch, .325" pitch, .063" gauge setup requiring 81 drive links.

Always verify your actual guide-bar specifications before ordering.

Product Specifications

• Manufacturer: STIHL
• OEM Part Number: 3639-005-0081
• Alternate Number: 36390050081
• Chain Model: 26RS 81
• Chain Type: Rapid Super
• Cutter Profile: Full chisel
• Bar Length: 20"
• Pitch: .325"
• Gauge: .063" / 1.6 mm
• Drive Links: 81
• Application: Firewood cutting, landowner use, and professional cutting
• OEM / Aftermarket: Genuine STIHL OEM

Why Choose STIHL Rapid Super?

The STIHL Rapid Super full-chisel cutter design is built for experienced users who want fast, aggressive cutting performance in clean wood.

Benefits include:

• Full-chisel cutters for fast cutting
• Genuine STIHL cutter geometry
• Designed for compatible Farm Boss® and professional saws
• Precise OEM chain specifications
• Proper fit when matched to the correct guide bar and sprocket
• No uncertainty about aftermarket cross-references

Full-chisel chains perform best in clean cutting conditions and are intended for users familiar with chainsaw operation.

Why Choose a Genuine STIHL OEM Chain?

Using a genuine STIHL OEM chain helps ensure the chain matches STIHL's intended specifications for compatible equipment.

Benefits include:

• Genuine STIHL construction
• Factory-specified pitch, gauge, and drive-link configuration
• Consistent cutter geometry
• Reliable fit when matched correctly
• No aftermarket substitutions
• Designed for compatible STIHL cutting systems

Why Buy From P&P Small Engines?

P&P Small Engines specializes in genuine OEM outdoor-power-equipment parts.

When you order from us, you get:

• Genuine OEM STIHL products
• Knowledgeable parts support
• Help confirming chain fitment
• Careful order fulfillment
• Support before and after your purchase

We help customers get the correct chain the first time.

Frequently Asked Questions

What is STIHL 3639-005-0081?

STIHL 3639-005-0081 is a genuine OEM 26RS 81 Rapid Super chainsaw chain with .325" pitch, .063" gauge, and 81 drive links.

What does STIHL 26RS 81 mean?

26RS identifies the STIHL Rapid Super chain configuration. 81 refers to the 81 drive links in this chain loop.

Is this a 20-inch STIHL chainsaw chain?

Yes. This chain is intended for compatible 20-inch guide-bar configurations requiring .325" pitch, .063" gauge, and 81 drive links.

Is STIHL 26RS a full-chisel chain?

Yes. STIHL Rapid Super RS uses a full-chisel cutter profile designed for fast cutting performance in clean wood.

Is this chain OEM or aftermarket?

This is a genuine STIHL OEM chain, part number 3639-005-0081.

Will this chain fit my STIHL MS 271 Farm Boss?

It can fit compatible MS 271 configurations using a 20-inch bar, .325" pitch, .063" gauge, and 81 drive links.

Verify your guide-bar specifications before ordering.

Will this chain fit my STIHL MS 261?

It can fit compatible MS 261 configurations that require this exact 20", .325", .063", 81-drive-link chain setup.

Will this chain fit my STIHL MS 291 Farm Boss?

It can fit compatible MS 291 configurations using the same chain specifications.

How do I make sure this chain fits?

Match all four specifications:

20-inch bar + .325" pitch + .063" gauge + 81 drive links

If any specification differs, you need a different chain.

Order STIHL 26RS 81 – 3639-005-0081

Choose genuine STIHL 26RS 81 Rapid Super chain when your compatible chainsaw requires a 20-inch, .325" pitch, .063" gauge, 81-drive-link full-chisel chain.

Need help confirming fitment? Contact P&P Small Engines before ordering and we'll help identify the correct OEM chain.