The hat itself and one size and is manufactured with lacrylique, thick and warm, perfect for winter cover their heads. It is possible to remove the earphones to wash the cap (although quun bit complicated).
The headphones work fine. They must be moving a bit to get directly at your ears and once in position the sound is good (all having different head circumference, so I suggest to move without the right earpiece until the commands have both headphones perfectly aligned with your ears). This is not the Hifi but the bass is very present, clear mids and trebles with an adequate volume for my needs. Lappairage Bluetooth is simple and trouble and running away (for me between 6-7mètres) is more than sufficient, and nest in any problematic case that your phone will be with you when you will use the cap. The control panel works happily and call quality is very good. The battery seems to hold about 2.5-3 hours and charging via micro USB is ultra fast.
In conclusion, this is a cap of high quality, perfectly functioning as a traditional cap or as a Bluetooth headset. I've had the opportunity to use a number of product August the last two years, and from experience, I can ensure that their products are of high quality and durable.
This cap seems to be a continuation of their products. If you want a hi-tech hat like this, I highly recommend it.