Several caveats
It heats up like it says, and fairly quickly. I used an infrared thermometer and the top maxed out at 113 F, and the concave eye portion at 83 F. The concave eye portion could get hotter if you press it into the heating layer. So the heat is largely influenced by the contour padding and air gaps.<br /><br />In that respect, it is a very efficient sleep mask, not putting pressure on the eyes, and providing a true blackout. There may be an issue around the nose area as everyone's noses are different. I end up with a slight peak-through at the most comfortable distance up from my nose if I look at it.<br /><br />The hook-and-loop strap is on the finer side, indeed less likely to trap hair but do move it out of the way. I don't have a particularly large head and there was only one inch left where I set it. So if you have a large head it may not be sufficient.<br /><br />The magnetic connection is nice, I find it tolerates a good amount of movement. Of course it will disconnect with enough force; much easier vertical than lateral, as there is a small peg reinforcing the connection. 39 inches is not all that much, especially since the control is half way, taking up some slack. It's fine if you are wearing a USB battery but difficult if it's tethered. The connection is on the left side if you're wearing it, which can pose a problem depending on where the power source is. You can use a USB extender cable but it's a hassle.<br /><br />It comes with a cold gel pack that sits in the concave area, and a sateen finish cinch bag for transport.<br /><br />In conclusion, it works and comfort was prioritized, but there are some issues. The more direct heat concentrated at the top is limited, and the concave area is effectively creating a low-temperature oven via radiant heat; more even heating and reaching 131 F would be large improvement. I would have appreciated an additional magnetic connection on the other side of the mask. The strap should be longer.
Rating: 4 stars