I like Zalman quiet case computer fans, which can be run off a 9V-12V wall wart. I use one to cool my enclosed HT system rack. The rack contains two digital cable boxes which generate a substantial amount of heat that needs to be vented 24/7.
https://www.fedex.com/fedextrack/index.html?tracknumbers=9612019317768870960479&cntry_code=us
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https://www.fedex.com/fedextrack/index.html?tracknumbers=9612019317768870960479&cntry_code=us
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