Nice. But where will you wear it? I can't see a party in our immediate future.

Right here. I've been swinging it round my head, squatting with it on my shoulders and even giving it the odd punch.

I know things are tough, but that's no way to treat an innocent Jimmy Choo.

This ain't no handbag. It's a HydroCore: a water-filled, take-anywhere fitness tool that's made a big, er, splash in the US - especially when Kate was spotted training with one.

More lifestyle:

This sounds fun. Tell me more.

The bag uses the power of water dynamics to build stability, strength, and explosiveness.

It's made of tough PVC and you just fill it from a tap.

Mine's a quarter-full right now, which is about 4.5kg. When it's empty it's super-light and portable.

Any other benefits to liquid lifting?

Remember Bruce Lee and his whole "be water, my friend", vibe?

It's about that. When you lift the bag, the water inside wants to keep moving in the direction you're swinging it.

All your muscles activate to help stabilize the water's constant unpredictable movement. It's a deeper, more focused workout.

Any fave moves when you're going with the flow?

I load the HydroCore onto my back for weighted lunges and squats and lift it in overhead presses and bent-over rows. And it adds serious sloshy substance to a kettlebell swing.

Something tells me this bag is badass.

It sure is. Created by Maurizio Tangari, trainer to MMA fighters and military personnel, it's inspired by Bulgarian shepherds who carried small farm animals on their shoulders, and in turn inspired Bulgarian wrestlers to train with unstable weights.

And it's even a built-in hydrator.

Funny you should say that.

Good-bloke that Maurizio - his Hydro Reach project is offering the HydroCore as a water transporter for women and girls in Africa who become injured and arthritic from carrying their families' daily water supply over long distances.

The bag can travel on shoulders, better distributing the weight. Plus it can also sit comfortably atop a donkey, cow or goat.

In a neat reversal of the whole animal-carrying concept!

Nice one Maurizio - this is definitely my bag.