Having had ventilation problems (mold) in an integrated top box that runs the length of our motor motor and an unsatisfactory 12v fan system it dawned on me that a solar powered extractor vent might be a good idea. We are currently in the South of France and last summer there was the added problem of several weeks of temperatures of over 40 degrees Celcius that made the inside of the vehicle sometimes very uncomfortable. The UltimateAddons low profile stainless steel solar extractor fan through the Amazon Marketplace looked to be appropriate quality. It was certainly the cheapest for the specification and almost half the price of an identical-looking model being advertised by a solar power specialist firm. It was easy to fit, has a very handy on/off switch at the end of four metres of cable which is more than enough for our needs. Actually it is a moot point because the unit is virtually silent even in full sun. You have to get within a metre of it to hear a whisper. As an added bonus it does not vibrate or hum either and this is perfect considering we sleep and work in the vehicle at various times. It is relevant at night because the fan continues periodically for several hours from dusk. It has not let water in during a torrential downpour, nor when driving in heavy rain. The mold problem and smell is abating after several days. It will not be powerful enough to extract serious heat from the vehicle so I have decided to order a second. This should go a long way to helping, bearing in mind it works in light, not just direct sunlight. Since I have just relocated the fridge inside the vehicle I can see it is a good idea to order a third to assist in the venting of the warm air (via the roof space rather than having to cut new grill/vent holes in the bodywork) from the fridge, since this has also been a problem in summer heat. I contacted the company with a concern about two rubber grommets loose in the box. Head of Customer Services responded within two hours and asked me to send a photograph. Two hours later they reassured me the 'grommets' were actually cut-outs from the foam base of the unit and not relevant to the unit's operation. On the whole you can't wish for better service or price (or delivery - four working days to France). Frequently in Amazon Marketplace goods are not described adequately. This is not the case with this item. Top marks to UltimateAddons. They are now on my Internet Favourites.