Action Replay card for jap Saturn only?

Well, yeah it's true.

Each system has a country lock out built into it, if the cartridge is made in japan for a jap Saturn then it wont be able to be used with a U.K or U.S.A saturn. All it can do is allow the use of Import CD's so using the jap PAR in a jap saturn and then puting in a U.S.A CD and then using the import feature of it will allow the use of that game.
To my knowledge these cards can work in any saturn, I have never seen anything to prove otherwise, especially since most PAR's are built in hongkong and I've seen people from america, england, and other places use them.
It's possible, but I don't see why anyone would do it since AFAIK the original AR carts made in England by Datel had multiregion booting from the beginning, so anyone reverse engineering/copying code from that would have to deliberately remove the signatures for other territories. It's probably a faulty assumption on the part of the seller.
ive seen the jap card b4 at my import shop, i almost bought it since it was the last one. i just bought the us one and it played imports but failed to supply the 4 megs.
They have some that have only the 1mb or no 1mb/4mb feature.. and they have a just the 4mb/1mb+stkey thing.. a few diff ones, i jus sold my Par4n1 (some call it 5 in 1 but no one uses the 5th function
) but its light gray and works fine.

And D-Boy has one thats Black and is older with just the 1MB + STKey functions and Cheat Device