Wear these to protect your fursuit head from your sweat and to keep you cool while you suit.
The two most trusted brands are UnderArmour and Schwampa.
UnderArmour typically has better construction and thinner material. It is the best if you keep your mouth covered while in suit.
Schampa is less expensive, cools about the same, and stays in place better. I use it when I don’t want my mouth covered. (Although both balaclavas can have mouth covered or uncovered.)
When looking for a balaclava, you want to make sure you are getting one made for hot weather, with material that will keep you cool (typically lycra or spandex/elastane).
If you get the wrong type of balaclava (one made for winter and keeping you warm) you may give yourself heat stroke.
For UnderArmour, the correct line is “HeatGear” and for Schampa, it’s “CoolSkin”. If you accidentally buy and/or use the wrong type of balaclava, you will know immediately once you put your fursuit head on. If you shop directly from this list, everything has been picked by hand, so you will not have to worry about buying the wrong type.
I have also added some other brands in here, but have no personal experience with brands other than Schampa and UnderArmour. Remember that the other brands will likely be smaller in size than Schampa and UnderArmour. Therefore, if your head is of a larger circumference, the other brands may be too tight.