The AH5 is the lightweight successor to the Divex free-flow AH3 and AH4 helmets. It is designed to be used either fitted with its own neck-seal, or locked directly into a dry suit. Because it combines many of the advantages of both the traditional hard-hat helmet and the modern diving mask, the AH5 is recommended for tasks as diverse as heavy construction, mobile inspection and protracted dives in cold and polluted waters. With an increased over-pressure option plus extra weights the helmet can be used in nuclear reactor fuel ponds. If the suit should leak then the increased over-pressure results in air escaping out of the suit and not water leaking inwards. Although the AH5 is light, it is extremely strong. The monocoque head shell is made from hand-laid impact resistant glass fibre.