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The Cauldryn Is A Travel Mug That Boils Or Keeps Your Drink Warm Using An Element

If you like your coffee warm long after you've poured it into your travel mug, this might be the perfect product for you.
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The Cauldryn is a prototype travel mug with a heating element that boils or keeps your drink warm.

One of the greatest issues facing travel muggers is having to glug on glacial grog.

Coffee (or any other beverage) doesn’t stay warm forever, even if it’s kept in the world’s best travel mug.

I don’t mind cold coffee. I’ll lick a block of ice if it’s laced with coffee.

But for many coffee aficionados, the idea of drinking cold coffee is akin to drinking baby mice wine. It’s not going to happen.

If cold coffee gives you the chills and every travel mug you’ve tried leaves you dissatisfied, there’s hope.

Number 6 Brands has created a prototype travel mug that keeps your drink warm using an element.

It reminds of those USB cup warmers you plug into your computer, but more advanced.

I emailed Jason Shinn, co-founder of Number 6 Brands, to get more info on their product, which they call the Cauldryn. He was kind enough to answer.

Let’s take a look.

How the Cauldryn works

The Cauldryn is a travel mug that sits on top of an element (called the Fyre) that boils the drink in the travel mug, or keeps it warm.


The Cualdryn comes with a 16 oz capacity.

It’s a popular size for travel mugs. I bought and reviewed the 16 ounce Contigo West Loop. It’s a lovely size for a travel mug; easy to handle.


The Fyre element comes in two models:

  • Fyre
    • A non-rechargeable element.
  • Fyre Mobile
    • A rechargeable element.


You can use the standard Fyre like a USB cup warmer. Plug it in and stand your Cauldryn on top of it.

It’s a mini kettle that boils up to 16 oz of liquid. Or it keeps your drink warm for as long as it’s plugged in.

Fyre Mobile

You can charge the Fyre Mobile and use it on the go. Charged, you get two full boils out of it. Or keep your drink warm for hours on end.

Charging time

The Fyre Mobile takes four hours to charge.

Easy to operate

The Cauldryn comes with two buttons. These allow you to turn on the Fyre or Fyre Mobile and switch between modes.


The Cauldryn Fyre Mobile features blue LED’s that indicate battery level, while the standard Fyre and Fyre Mobile feature yellow and red LED’s that show the travel mug’s current operating mode.


The vacuum insulated design makes the mug safe to handle. It won’t burn your hands, since it doesn’t allow heat to escape.

The Cauldryn is at its warmest where the mug and element meet, but it’s a cup-of-cocoa warm, not scorching hot.

The travel mug itself never exceeds room temperature.

Spill proof

The Cauldryn is spill and leak-proof. Flip it upside down if you want. Your drink stays inside.


The Cauldryn is made from stainless steel. I take it they use a food grade stainless steel.

Variable heat

I’m not sure why there are two hot temperatures, but the Cauldryn offers an amazing heat range.

Powering it

The Cauldryn comes in 110V option for now, with an optional 12V base.

It comes with an AC charging cord. For $10 you can buy a DC car charger base.

The Cauldryn does not come with a USB charger. You cannot plug it into a USB port. Mr Shinn says that a USB cable does not provide adequate power.

Number 6 Brands will add a 220V option soon.

Size & weight

Please note that they haven’t finalized the product yet.

Will it fit into a cup holder?

The bottom diameter of the Cauldryn is 88.9 mm (3.5 inches) in diameter.

So it depends on the cup holder size.

It won’t fit in any of our vehicles. The Contigo, with a diameter of ~2,9in (~74mm), fits fine.

Train smash? Nope.


You can get the Cauldryn at the following prices:

  • Cauldryn Fyre
    • Indiegogo – $50
    • Retail price – $69.99
  • Cauldryn Fyre Mobile
    • Indiegogo – $100
    • Retail price – $129.99


The Cauldryn is available only in the USA.

I’m sure they’ll release it worldwide once demand grows.

Final thoughts

If the thought of sipping on cold coffee doesn’t sit well with you, consider supporting the Cauldryn.

This vacuum insulated stainless steel travel mug comes with an element that keeps your drink warm at your choice of four heat levels.

The rechargeable model lets you go all day with a single brew that remains hot.

It’s the perfect tool for enjoying a cup of AeroPress coffee in.

Let’s see if Number 6 Brands can bring this travel mug to life.

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