Wish i'd have seen others guides before buying some Mach 3 Turbo blades. They looked real, but put side by side with a real one you could see that the real blades had Gillette stamped on them, the rubber fins on the real ones were far softer than on the fakes. Also the plastic casing which holds every 4 blades had a serial number on the real ones but didn't for the fakes. And the biggest difference is that shaving with the fakes ripped the skin from my face. Luckily i was off work, but the burning sensation / redness took 3 days to dissapear.
One final note .......... be aware that ebay don't care and won't help when things go wrong, i tried to contact them but only received silly automated messages asking me to select my problem from a given list. None of the options related to fake blades. I'm sorry to say i have cut down my useage of ebay and will now only purchase items if they really are hard to find elsewhere.