I can only state problems found with those for a nissan terrano and well echoed by other owners and that is they dont last and often are only good for 5-10 minutes running before the ecu rejects them.Also i bought an ebay one for a mercedes E200 a few years back,same issue ,ran great for 3 miles then back to a type of limp mode,in each case the genuine maf resolved the problem . It has been suggested the impedance of the internals just isn`t what it should be causing the ecu to not want to play with them anymore.Have bought from good reputable ebayers and they replace them only for the replacement to eventually do the same or immediately do the same.,its a pain in the arse sending them back,incurs costs and you end up regretting a cheap fix plus the main dealer part would normally have a 12 months warranty,more cost but peace of mind and unless you get totally perfect running with the ebay ones you cant rule out that they are not quite fixing any problem 100%.