Insulin Cooling Battles: Breast Pads vs Breezy Packs

This is part of an on-going series where I compare different technologies available for keeping insulin cool so it does not spoil.

Previous battles were:

In this battle I compare Breezy Packs to breast pads.

Why Breast Pads?

It may seem like a curious choice but there is method to it. In “Frio vs Breezy Packs” I mentioned that Breezy Packs use Phase Change Materials (PCMs) to maintain the internal temperature. For a rundown of the physics on how they work, head over to that post.

While the specific material used in Breezy Packs is a trade secret, one candidate substance is octadecane whose melting point is around 28C (82.5F). While not listed on the box, on eBay the listing for the breast pads had octadecane as one of the main ingredients. For $20 it was worth a shot.

Sure enough, on touching the pad there was a cooling sensation so things were promising.

The Setup

For Breezy Packs, I used their smallest size and put one of my Ozempic pens inside with a digital temperature sensor embedded within it.

For the breast pads, I used a mesh pencil case I had picked up and layered the breast pads inside with another pen with a sensor between them.

In the image you only see the pads on one side but I did put eight on one side and eight on the other for the experiment.

A third sensor was used to track the oven temperature.

With the two containers on a rack on an oven tray (I did not want the tray to be in direct contact with the containers) I placed them in the oven and took the temperature around every five minutes until one of the containers went past 30C (86F).

Prior to entering the oven, the breast pads consistently measured a lower temperature than the Breezy Pack. I assume this was because of the higher area of contact between the pads and the insulin pen. However, things changed when the oven became involved.

The Results

While the breast pads initially showed a lower temperature, this soon changed. Both were pretty stable but, at 17:15, the temperature of the oven was continuing to fall and was heading towards 30C so I increased the dial by a small amount. The different response can be seen with the breast pads increasing temperature much faster than the Breezy Pack and eventually hitting 30C. In fact, over 40 minutes, the breast pad temperature went up by 7C (12F) compared to 2C (3F) for the Breezy Pack.


Breezy Packs wins again although I suspect if we used a similar volume/weight of breast pad PCM the result may have been different. This being said, the amount of breast pads needed to achieve this would be excessively expensive. As with previous experiments, the components were fully funded by myself without commercial sponsorship of any kind.

2 thoughts on “Insulin Cooling Battles: Breast Pads vs Breezy Packs

  1. Sandra March 29, 2022 / 8:20 am

    Thank you for your interesting experiments and observations.
    What would happen if you put the Breast pads around the pens inside the breezy pack?
    I am
    Particularly interested in being able to transport pens and keep the cool ad I am travelling from Adelaide to Sydney regularly now.
    Can you please tell
    Me where you get the breezy packs? Are they similar to the Frio packs?


    • leontribe March 29, 2022 / 2:04 pm

      Hi Sandra,
      Given the breast pads use similar materials to the Breezy Packs I expect it would simply increase the longevity of their ability to keep the contents at temperature but, to be honest, the Breezy Packs are pretty good on their own in my experience.

      The Breezy Pack on its own should cover the trip between Adelaide and Sydney, especially if you are mostly in a car or plane where the temperature is unlikely to go over 30C. To be sure, you can get a MedAngel ( which is a Bluetooth temperature sensor that allows you to monitor the internal temperature via your phone.

      Breezy Packs also have larger sizes which last longer. Breezy Packs are available from . The main difference between Breezy Packs and Frio is you do not need to soak Breezy Packs; they use PCMs to get a similar cooling effect. I talk about the difference in the Breezy vs Frio article 😉


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s