Buzzy and noisy...very expensive unless you get them off ebay.
Don't know how anyone plays without this. Local field plays every night...we're near the ocean and people are ALWAYS walking out of games with fogged lenses. Doesn't matter if they have "thermal" or whatever...you play hard, start sweating on a humid cool night and you are toast.
For me, I wear glasses and it was hopeless...got the JT glasses inserts, took them to Lens Crafters and had them made to perscription and then got the fan...use it every time I play and couldn't play without it.
If you've never needed it...great...if you've even ONCE had problems with fogging, this is the solution. Pain in the butt to mount on some masks but if you can't see, you can't play and this'll fix that.