The jaw mounted CPU cooling fan. Note the small switch located next to the 9V battery. I can operate this switch just as easily while wearing the Bucket and in full armor.
Small squares of foam were secured to the Bucket, capped with Velcro. Matched Velcro pieces were carefully affixed - they do not interfere with the operation of the fan - to the corners of the cooling fan. There is absolutely NO vibration noise, just the actual sound of the fan blade assembly. Since the batteries are only 9volts and the fans are rated for 12v, the net result is a fairly quiet fan. I've heard of some Troopers thinking of switching to 12volt battery packs, but the fans will likely be significantly louder.