I got these with a photochromic lens which is nice and definitely works. The instant moisture enters this lens the fan does not dissipate it or at least in time. Using them on a cold day the moisture will be there anyway and freeze providing a constant fog for your day. Even after I dried them out multiple times they continued to develop a film in the middle of the lens. Smith with this goggle you made a great day bad. Definitely dont waste your money on the fan Smith's regular goggles work just fine, the fan wont fix your fogging problems. The buzzing from the fan will also provide you with hours of fun. Sometimes I day dream and imagine bees chasing me down the mountain or an airplane over head, either way I skied faster, maybe because I couldnt see or maybe because I thought something was chasing me.