Just when you think you've seen every exotic and unusual material used to create audio equipment, something rolls up and surprises you. Today, that honour goes to Grado Labs and its latest in high-fidelity - the Hemp Headphone that costs 420 dollars.

We're told that the team at Grado had to draw on inspiration and experience from past Limited Editions. The Brooklyn-based brand took what they learned from working with exotic woods, such as cocobolo, they fine-tuned the drivers to work in tandem with the wood and hemp composite that, together, form that smokey swirly pattern. The highly compressed hemp creates a damping effect and, so say Grado, produces a fuller sound. The result is a claimed 13Hz – 28kHz frequency response. Nothing weedy about those figures.

Getting the balance just right, not too loose or too tight, proved to be a joint effort with the hemp doing the heavy lifting and the maple helping to even things far out.

Jonathan Grado told StereoNET:

This is some of the most fun we've ever had with a limited edition. We had no clue how they'd turn out, but they ended up sounding pretty amazing. It also reminded us to stock up on more snacks at the office.

The open-backed Hemp Headphones certainly sound like they would be popular and be passed around between friends to take their turn. Grado adds that the Hemphones are a slow burn, continually getting better with every listen.

Order a pizza, get some cookies and chill with the Grado Hemp Headphones which are available for pre-order at $420 US - of course they are.

In the UK the hemphones have a less tongue-in-cheek pricing of £479.95

For more information, visit Grado.