---
product_id: 335129091
title: "JUST1 J39 Reactor Thermoplastic Resin External Shell MX Off-Road Motocross Motorcycle Helmet (Flat Black, Medium)"
brand: "just 1"
price: "€ 16.96"
currency: EUR
in_stock: true
url: https://www.desertcart.ie/products/335129091-just1-j39-reactor-thermoplastic-resin-external-shell-mx-off-road
store_origin: IE
region: Ireland
---

# Double-D retention system for secure fit 14 total vents for superior airflow and cooling Thermoplastic resin shell for ultimate impact resistance JUST1 J39 Reactor Thermoplastic Resin External Shell MX Off-Road Motocross Motorcycle Helmet (Flat Black, Medium)

**Brand:** just 1
**Price:** € 16.96
**Availability:** ✅ In Stock

## Summary

> 🏁 Ride Bold, Ride Safe – The J39 Reactor Means Business

## Quick Answers

- **What is this?** JUST1 J39 Reactor Thermoplastic Resin External Shell MX Off-Road Motocross Motorcycle Helmet (Flat Black, Medium) by just 1
- **How much does it cost?** € 16.96 with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.ie](https://www.desertcart.ie/products/335129091-just1-j39-reactor-thermoplastic-resin-external-shell-mx-off-road)

## Best For

- just 1 enthusiasts

## Why This Product

- Trusted just 1 brand quality
- Free international shipping included
- Worldwide delivery with tracking
- 15-day hassle-free returns

## Key Features

- • **Breathe Easy:** 8 intake and 6 exhaust vents optimize airflow to beat the heat
- • **Secure & Ready:** Trusted double-D ring closure ensures your helmet stays locked in place
- • **Custom Comfort Fit:** Two shell and EPS sizes plus removable cheek pads with emergency quick-release
- • **Stay Fresh, Ride Longer:** Removable, washable inner lining designed for all-day freshness
- • **Precision Engineered Safety:** ECE 22/05 & DOT certified to keep you protected on every ride

## Overview

The JUST1 J39 Reactor helmet combines a high-quality thermoplastic resin shell with advanced ventilation and safety certifications (ECE 22/05, DOT). Designed for motocross enthusiasts, it features dual shell sizes, removable emergency cheek pads, and a washable interior, delivering a perfect blend of protection, comfort, and style for serious off-road riders.

## Description

Full description not available

## Features

- High quality thermoplastic resin External Shell, 2 SHELL SIZES, 2 EPS SIZES
- Removable cheek pads with the “J.1.E.R.” (JUST 1 Emergency Remove), Double-D retention system
- Removable and washable inner lining, 8 INTAKE and 6 EXHAUST VENTS
- Homologated ECE 22/05, DOT Approved
- Meet Federal Motor Vehicle Safety Standard (FMVSS) 218

## Technical Specifications

| Specification | Value |
|---------------|-------|
| Sport | Motocross |
| Certificate Type | DOT |
| Shell Type | Hard |
| Specification Met | DOT, ECE |
| Shape | Oval |
| Closure Type | Double Ring |
| Manufacturer | JUST 1 |
| Model Name | J39 |
| Item Package Dimensions L x W x H | 15.75 x 13.25 x 11 inches |
| Package Weight | 2.11 Kilograms |
| Brand Name | Just 1 |
| Suggested Users | unisex-adult |
| Part Number | J39 |
| Model Year | 2020 |
| Outer Material | Thermoplastic Resin |
| Size | Medium |

## Product Details

- **Color:** Reactor Flat Black
- **Brand:** Just 1
- **Vehicle Service Type:** Off-Road Bike
- **Item Weight:** 2.11 Kilograms
- **Material:** Expanded Polystyrene (EPS), Thermoplastic

## Images

![JUST1 J39 Reactor Thermoplastic Resin External Shell MX Off-Road Motocross Motorcycle Helmet (Flat Black, Medium) - Image 1](https://m.media-amazon.com/images/I/61zIcuxff8L.jpg)
![JUST1 J39 Reactor Thermoplastic Resin External Shell MX Off-Road Motocross Motorcycle Helmet (Flat Black, Medium) - Image 2](https://m.media-amazon.com/images/I/61BeVloYbPL.jpg)
![JUST1 J39 Reactor Thermoplastic Resin External Shell MX Off-Road Motocross Motorcycle Helmet (Flat Black, Medium) - Image 3](https://m.media-amazon.com/images/I/51WdIQE-MuL.jpg)
![JUST1 J39 Reactor Thermoplastic Resin External Shell MX Off-Road Motocross Motorcycle Helmet (Flat Black, Medium) - Image 4](https://m.media-amazon.com/images/I/51NUw-iYzJL.jpg)

## Frequently Bought Together

- Just1 Racing J39 Thermoplastic Resin External Shell MX Off-Road Motocross Motorcycle Helmet
- Dmeixs Motorcycle Goggles Dirt Bike Goggles Grip For Helmet Anti UV Windproof Dustproof Anti Fog Glasses for ATV Off Road Racing with Cool Look Headwear Silver Lens 2 in 1

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**Shop now:** [https://www.desertcart.ie/products/335129091-just1-j39-reactor-thermoplastic-resin-external-shell-mx-off-road](https://www.desertcart.ie/products/335129091-just1-j39-reactor-thermoplastic-resin-external-shell-mx-off-road)

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*Product available on Desertcart Ireland*
*Store origin: IE*
*Last updated: 2026-02-06*