I have 2 of them in my 12cf. One is sufficient in an 8cf or less. The fans have a very low current draw and are relatively quiet. After sitting all Winter, the first fan that was purchased early last year decided that one of its fans did not want to start up. I gave the blade a spin and it went to work, but it is noisy now. For the price, I can't really complain especially since that fan ran 24/7 for about 5 months last year.
Without the fans, on the highest setting (9) my fridge would struggle to maintain much less than 38-40* in the heat of the Summer. Now with the 2 fans and the fridge set to #7, it will maintain 33-35* with no problem. The fans also prevent ice buildup on the coils. Ice buildup probably isn't a problem in places like Arizona, but here on the swampy climate of the East Coast, it can be a big problem.
By the way, that ebay seller is good to deal with. I had 2 separate transactions with them and both times the fan arrived in less than 2 days.
2011 Ford F-350 4X4 CC LB SRW 6.7
2013 Keystone Fuzion 315
B&W Companion Hitch
1 wife 2 kids and 1 dog