1 6

Fourth Element

Available to Order

Fourth Element Halo AR Undersuit

Fourth Element Halo AR Undersuit

RRP $980.00 AUD

Our Price $849.00 AUD

You Save $131.00 AUD (13%)

Shipping calculated at checkout.

In stock
View full details

Product overview

About this product

The Fourth Element HALO A°R is the flagship drysuit undersuit in the Fourth Element thermal range, engineered for divers who demand maximum warmth without unnecessary bulk. Featuring advanced A°RGON™ aerogel insulation originally developed for aerospace and cryogenic applications, it delivers exceptional thermal efficiency while maintaining outstanding flexibility and freedom of movement beneath modern drysuits.

Designed for technical diving, CCR, cave diving and demanding cold-water expeditions throughout Melbourne, Victoria and Australia, the HALO A°R provides dependable thermal protection during extended dives where maintaining body temperature is critical. Pair it with the J2 or Xerotherm baselayers to create the ultimate Fourth Element cold-water layering system.

The Fourth Element HALO A°R Undersuit is a premium cold-water drysuit undergarment engineered for exceptional thermal protection with minimal bulk. Using advanced A°RGON™ aerogel insulation technology originally developed for aerospace and cryogenic applications, it delivers outstanding warmth while maintaining flexibility and freedom of movement.

Designed using body-mapped insulation, the HALO A°R concentrates warmth where it is needed most while reducing unnecessary bulk. The water-repellent stretch outer fabric, offset front zipper, thumb loops, foot stirrups and P-valve access make it an excellent choice for both recreational and technical divers spending extended time in cold water.

Available in men's and women's sizing. Most sizes are available to order with fast Australia-wide shipping.

Service and support

Shipping and specialist support

Why buy from Extreme Watersport

  • A°RGON™ Aerogel Insulation
  • Designed for Cold Water Diving
  • Available in Men's & Women's Sizes

Shipping

Available to Order. Many popular sizes are stocked locally. If your selected size requires supplier transfer, most orders dispatch within 3–5 business days. We'll always contact you promptly if a longer lead time applies.

Lead time

Available to Order.
Many popular sizes are stocked locally. If your selected size requires supplier transfer, most orders dispatch within 3–5 business days.

Technical construction

Why Choose the HALO A°R?

The HALO A°R is designed for divers who need maximum warmth without the bulk traditionally associated with expedition-weight undergarments. By combining advanced A°RGON™ aerogel insulation with body-mapped thermal protection, it delivers outstanding comfort during long dives while maintaining excellent flexibility and buoyancy characteristics.

Performance detail

Performance highlights

Highlight

A°RGON™ Aerogel Insulation

Advanced aerogel insulation technology provides exceptional thermal performance while remaining lightweight and highly compressive.

Highlight

Body-Mapped Warmth

Extra insulation is placed around the body's core and other critical areas to maximise warmth without restricting movement.

Highlight

Technical Diving Ready

Designed for extended cold-water dives with thumb loops, foot stirrups and dedicated P-valve access.

Highlight

Low Bulk, High Performance

Outstanding thermal efficiency from a thinner undergarment reduces bulk while improving comfort and buoyancy control.

Specifications

Technical Specifications

Product Type
Premium drysuit undersuit
Thermal Insulation
A°RGON™ aerogel insulation with body-mapped construction
Outer Fabric
Wind and water-repellent stretch fabric
Inner Fabric
68% Polyester, 32% Recycled S.Cafe® Polyester
Outer Composition
83% Polyester, 13% PU, 4% Elastane
Fit
Men's and women's ergonomic sizing
Features
Thumb loops, foot stirrups, offset front zip and P-valve access pocket
Suitable For
Trilaminate and neoprene drysuits
Care
Machine washable
Country of Manufacture
Made in China

Fit guidance

Need help choosing your size?

Use the size guide below as a reference before ordering. If you are between sizes or plan to wear additional base layers, contact us and we can help recommend the most suitable fit.

Men's size guide
Fourth element size chart
Women's size guide
Fourth Element Women's Size chart

Included

What's Included

  • Fourth Element HALO A°R Undersuit
  • Manufacturer packaging
  • Care instructions

Product guidance

Product guidance

Why Choose the Fourth Element HALO A°R?

The Fourth Element HALO A°R is the flagship thermal undersuit in the Fourth Element range, designed for divers who demand exceptional warmth in the coldest diving environments. Using advanced A°RGON™ aerogel insulation, originally developed for aerospace and cryogenic applications, the HALO A°R delivers outstanding thermal efficiency while maintaining flexibility, mobility and comfort beneath a drysuit.

Unlike traditional bulky undersuits, the HALO A°R uses body-mapped insulation to place warmth exactly where it is needed most. This reduces unnecessary bulk while allowing unrestricted movement during valve drills, propulsion techniques and extended decompression stops, making it ideal for recreational, technical and CCR diving.

Built for Melbourne and Australian Cold-Water Diving

Cold-water diving throughout Melbourne, Port Phillip Bay, Victoria and Tasmania demands dependable thermal protection that performs dive after dive. Whether you're exploring local wrecks, conducting instructor training or completing long technical dives, the HALO A°R helps maintain core warmth while remaining comfortable throughout extended bottom times.

Its advanced insulation technology makes it an excellent choice for divers who regularly dive through winter or frequently travel to colder destinations around Australia and overseas.

HALO A°R vs Arctic X: Which Fourth Element Undersuit Is Right for You?

Both the HALO A°R and Arctic X are premium drysuit undersuits, but they are designed for different levels of thermal protection. The Arctic X offers an excellent balance of warmth, flexibility and low bulk for year-round cold-water diving, while the HALO A°R is engineered for the coldest conditions, extended decompression dives, cave diving, CCR diving and demanding expedition environments where maximum insulation is required.

If you're unsure which undersuit best suits your diving, our team can help you compare the complete Fourth Element thermal range based on your local water temperatures, drysuit configuration and diving style.

Build the Ultimate Fourth Element Layering System

For maximum thermal performance, pair the HALO A°R with the Fourth Element J2 or Xerotherm baselayers to create a complete cold-water layering system. This modular approach efficiently manages moisture while maximising insulation, allowing divers to stay warmer and more comfortable throughout long recreational, technical and expedition dives.

Why Buy Your HALO A°R from Extreme Watersport?

Extreme Watersport is an authorised Fourth Element dealer in Australia, supplying genuine Fourth Element products backed by expert advice from experienced cold-water and technical divers. Whether you're upgrading your current undersuit or building a complete drysuit layering system, we'll help you choose the right combination of J2, Xerotherm, Arctic X and HALO A°R products for your diving conditions throughout Melbourne, Victoria and Australia.

Product help

Product FAQs

What water temperature is the Fourth Element HALO A°R designed for?

The HALO A°R is designed for cold-water diving where maximum thermal protection is required. It performs exceptionally well in the waters around Melbourne and Victoria, particularly when paired with a quality trilaminate drysuit. The ideal thermal setup will still depend on water temperature, dive duration and your personal tolerance to cold.

Can I wear the HALO A°R with any drysuit?

Yes. The HALO A°R is compatible with most trilaminate and compressed neoprene drysuits. It is suitable for both recreational and technical diving, provided the drysuit has enough room to allow the insulation to loft correctly without restricting movement.

Do I need to wear a base layer underneath the HALO A°R?

For the best moisture management and comfort, many divers choose to wear a lightweight base layer such as the Fourth Element J2 or Xerotherm beneath the HALO A°R. Depending on water temperature and personal preference, some divers may also wear the HALO A°R on its own.

Is the HALO A°R suitable for technical diving?

Yes. The HALO A°R was developed with technical diving in mind and includes features such as body-mapped insulation, an offset front zip to minimise heat loss in horizontal trim, thumb loops, foot stirrups and a dedicated P-valve access opening. It is well suited to extended decompression, cave and wreck diving.

How should the HALO A°R fit?

The undersuit should fit comfortably without being excessively tight or restrictive. The insulation performs best when it can maintain its loft beneath your drysuit. If you're unsure which size is right for you, our team can help compare your measurements with the official Fourth Element size guide before ordering.

How do I wash and care for the HALO A°R?

The HALO A°R is machine washable following Fourth Element's care instructions. Allow the garment to dry completely before storage, and avoid compressing it for extended periods to help preserve the performance of the insulation.

Need Help Choosing the Right Undergarment?

Choosing the right thermal protection depends on your drysuit, water temperature, dive duration and personal cold tolerance. Contact our experienced team for personalised advice before placing your order.

Ask a dive professionalBack to Drysuit Undergarments