---
product_id: 41068174
title: "Ferrofluid 900uL General Purpose for 4 Inch Diameter Coil"
brand: "ferrotec"
price: "¥6489"
currency: JPY
in_stock: true
reviews_count: 5
url: https://www.desertcart.jp/products/41068174-ferrofluid-900ul-general-purpose-for-4-inch-diameter-coil
store_origin: JP
region: Japan
---

# Boosts power handling Optimized for 4-inch coils 900uL precision volume Ferrofluid 900uL General Purpose for 4 Inch Diameter Coil

**Brand:** ferrotec
**Price:** ¥6489
**Availability:** ✅ In Stock

## Summary

> 🎵 Elevate your audio—because your speakers deserve a glow-up!

## Quick Answers

- **What is this?** Ferrofluid 900uL General Purpose for 4 Inch Diameter Coil by ferrotec
- **How much does it cost?** ¥6489 with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.jp](https://www.desertcart.jp/products/41068174-ferrofluid-900ul-general-purpose-for-4-inch-diameter-coil)

## Best For

- ferrotec enthusiasts

## Why This Product

- Trusted ferrotec brand quality
- Free international shipping included
- Worldwide delivery with tracking
- 15-day hassle-free returns

## Key Features

- • **Power Handling Pro:** Enhances thermal capacity so your drivers perform louder and longer without compromise.
- • **Complete Repair Kit:** Includes cleaning strips and step-by-step instructions for a professional-grade restoration.
- • **Distortion Demolisher:** Damps resonance impedance to deliver crystal-clear, distortion-free sound.
- • **Universal Upgrade Potential:** Compatible with most compression drivers and diaphragm assemblies—upgrade your sound game effortlessly.
- • **Precision Engineered 900uL Dose:** Exact volume tailored for 4-inch voice coils ensures flawless performance.

## Overview

The Ferrofluid 900uL General Purpose kit is a precision-engineered solution designed for 4-inch diameter voice coils. It reduces distortion and increases thermal power handling by damping impedance at resonance, improving the clarity and durability of high-frequency and midrange drivers. The kit includes synthetic ester-based ferrofluid, cleaning strips, and detailed instructions, making it ideal for repairing or upgrading most compression drivers and diaphragm assemblies.

## Description

Our ferrofluid kits come with pre-measured packets of ferrofluid which are used to replace the old fluid in speaker air gaps when replacing diaphragm and coil assemblies. Ferrofluid improves the performance of high frequency and midrange drivers. It works by damping the impedance at resonance to effectively lower distortion, smooth frequency response, and increase thermal power handling. Ferrofluid improves the performance of high frequency and midrange drivers. It works by damping the impedance at resonance to effectively lower distortion, smooth frequency response, and increase thermal power handling. It should be used to replenish drivers treated previously with ferrofluid. With care, it can also upgrade most drivers that have never contained ferrofluid. The kits listed are approximate fill quantities relative to approximate voice coil diameters. In general, the air gap should be 75% filled prior to inserting a voice coil diaphragm assembly. The kit contains synthetic ester-based ferrofluids and in most cases should not pose any adhesive incompatibility. It is recommended that this is confirmed by contacting the driver manufacturer prior to usage. Adding ferrofluid to a driver not intended for it will, in most cases, void the original manufacturer's warranty. Included in kit: A ferrofluid packet, absorbent paper strips for removing old ferrofluid, detailed instructions, and material safety data sheet.

Review: Extra good - Excellent didn’t job restoring my speakers tweeters.
Review: So good i ordered more! - Great stuff right there

## Features

- Ferrofluid Repair Kit: comes complete with cleaning strips and instructions
- 900uL for 4" voice coil
- Reduces distortion
- Increases power handling
- For most compression drivers, repairs, and diaphragm assemblies

## Technical Specifications

| Specification | Value |
|---------------|-------|
| ASIN | B00HX0L2XO |
| Best Sellers Rank | #1,304 in Speaker Repair Products |
| Customer Reviews | 4.6 4.6 out of 5 stars (22) |
| Date First Available | January 17, 2014 |
| Item Weight | 4.2 ounces |
| Manufacturer | Ferrotec |

## Images

![Ferrofluid 900uL General Purpose for 4 Inch Diameter Coil - Image 1](https://m.media-amazon.com/images/I/41xvce1alkL.jpg)
![Ferrofluid 900uL General Purpose for 4 Inch Diameter Coil - Image 2](https://m.media-amazon.com/images/I/61nLZrE8ctL.jpg)

## Customer Reviews

### ⭐⭐⭐⭐⭐ Extra good
*by D***Z on December 14, 2024*

Excellent didn’t job restoring my speakers tweeters.

### ⭐⭐⭐⭐⭐ So good i ordered more!
*by G***K on April 10, 2024*

Great stuff right there

### ⭐⭐⭐⭐⭐ replace more often than every 30 years
*by I***R on January 13, 2019*

This kit brought back my ~30 year old Vifa D25AG back to its former self. The old ferrofluid had dried out and was gummy like earwax or worse. Tried using solvent like acetone and OS-10, but that was not super effivient but OK. You don't have to squeeze the fluid out, it gets pulled out in a fine stream from 8mm away, so only a small hole is needed. I used half of the 900ul for two 1" tweeters.

## Frequently Bought Together

- Ferrofluid 900uL General Purpose for 4 Inch Diameter Coil
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- CMS MAGNETICS - (2oz Kit) Ferrofluid Science Experiment Kit for Education in Magnetism - Includes: 2 Fluid Ounce (59mL) Bottle of Ferrofluid, Gloves, Pipette, Petri Dishes

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**Shop now:** [https://www.desertcart.jp/products/41068174-ferrofluid-900ul-general-purpose-for-4-inch-diameter-coil](https://www.desertcart.jp/products/41068174-ferrofluid-900ul-general-purpose-for-4-inch-diameter-coil)

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*Product available on Desertcart Japan*
*Store origin: JP*
*Last updated: 2026-03-05*