How can I tell if authentic ProAc 2.5 or knockoffs

I have a chance of buying a pair of used Proac 2.5 for a good price, but there are nothing on the speakers that say the are 2.5s. No ProAc logo on the tweeter, no sticker or serial # on the back. I know there are some DIY kits out there, so I just want some inputs from you guys...Thanks.
Proac's all should have a metallic logo sticker on the back with the model no.,serial number etc.
The grilles should also have a logo on and the tweeter also.
You seem to be aware of this by your post.
They also come with a manual.
Personally I would avoid these and your instincts seem to say the seems very unlikely to me these are Proacs.
It should be obvious that they are or not. Just as Ben had said also the dust cap for the driver should have Proac on it. If none of these exsist I would say first of all, who is the guy? Are they for sale here at AG? I would go with your gut.
I seem to remember something about proac knock offs in the diputes section of audiogon. Maybe you do a search there.

From guy in a a White Van???
ProAc 2.5 are easy to repeat and it was done already numerous of times by DIY-ers.
The raw materials to build them are near $400 probably including shipping and taxes if applied.
Not from a guy in a white van! LOL! This guy was getting rid of all his equipments locally. He had some really expensive Audio Research tube preamp & amp so I didn't think he would pair them with imitations. He told me he had bought them second hand from a previous owner. I was kinda suspicious because these didn't have grills nor the holes to hold the grills. He even offer to take the midrange driver & tweeter to show me the inside. The drivers were all Scan Speak & the crossover did say "Proac". The finish was maple strangely similar to the DIY kits posted on the net. I think he got ripped off from the previous seller then which is kinda sad. He wanted $1300. The cabinets must have been knock offs then I believe. Anyway I trusted my instinct & did not buy. Just a good learning experience & as the say "let the buyer beware". Thanks guys...