# Stairmaster 4000PT Stepper Cog Cogged Drive Belt 21 (MX418)

\## StairMaster 4000PT Stepper Cogged Drive Belt 21 (MX418)

The StairMaster 4000PT Stepper Cogged Drive Belt 21 is a preowned replacement drive belt for the StairMaster 4000PT stepper. This belt forms part of the machine’s drive system and is intended to replace the corresponding original cogged belt when the existing part needs replacement. If you are repairing or refurbishing a StairMaster 4000PT, this specific part may help you restore the correct belt configuration without replacing the entire machine.

## Product Details and Benefits

This product is a cogged drive belt identified as \*\*MX418\*\*. It is listed for the \*\*StairMaster 4000PT Stepper\*\* and carries the product designation \*\*Drive Belt 21\*\*. The cogged design matches the type of belt used in the stepper’s drive mechanism, where the belt works with compatible drive components to transfer movement through the equipment.

The belt is sold in \*\*preowned condition\*\*. Each part has been carefully inspected by skilled technicians before sale to support safe and reliable use. Because this is a used fitness equipment part, it may show signs of previous service or handling. Choosing a preowned replacement can also help reduce waste by extending the useful life of existing fitness equipment and keeping serviceable components in use.

This listing is for the belt itself. The product page does not provide additional specifications such as material, belt length, belt width, color, or package quantity, so buyers should rely on the listed part identity and confirm the required specification before ordering.

## Compatibility and Applications

The \*\*StairMaster 4000PT Stepper Cogged Drive Belt 21 (MX418)\*\* is identified for use with the \*\*StairMaster 4000PT Stepper\*\*. It is intended as a replacement for the matching original drive belt in that equipment.

This part may suit customers who maintain commercial or home fitness equipment, service StairMaster machines, or restore an older 4000PT stepper. It can be considered when the existing belt has worn out, become damaged, or requires replacement during equipment maintenance. Confirm that your machine is the StairMaster 4000PT Stepper and that the original belt uses the same MX418 or Drive Belt 21 identification before purchasing.

\## Why Choose This Replacement Part?

A model-specific replacement part can make equipment repairs easier by matching the original machine application. This preowned StairMaster belt has been inspected before sale, giving repair professionals and equipment owners a clearly identified part for the 4000PT Stepper. Reusing a suitable fitness equipment component can also provide a practical alternative to discarding or replacing the complete machine.

## Before You Buy

\- \*\*Brand:\*\* StairMaster  
\- \*\*Product:\*\* 4000PT Stepper cogged drive belt  
\- \*\*Part number/SKU:\*\* MX418  
\- \*\*Part designation:\*\* Drive Belt 21  
\- \*\*Compatible equipment:\*\* StairMaster 4000PT Stepper  
\- \*\*Condition:\*\* Preowned  
\- \*\*Serial numbers shown:\*\* 35914 and 37486

Pictures are provided for reference. Stock may include multiple units, so the part may look slightly different from the photographed item. The seller states that each item remains the exact model and part listed. Contact the seller if you need additional information before ordering.

## Details

- **Price:** 29.99 USD
- **Vendor:** StairMaster
- **Type:** Miscellaneous
- **Tags:** All

## Variants

| Variant | Price | Available |
|---------|-------|-----------|
| Default Title | 29.99 USD | In stock |

## Images

- MX418
- MX418
- MX418
- MX418

## Additional Information

- **Condition:** PREOWNED

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> Source: [Cardio Equipment Parts](https://www.cardioequipmentparts.com/products/stairmaster-4000pt-stepper-cog-cogged-drive-belt-21-mx418)
> Updated: 2026-08-29