Ah yes, the joy of "standard" fin boxes in boards.
You will need a different fin for each type of box.
You may be able to get a tuttle fin into a deep tuttle box, but some packing on top of the fin may be advisable.
Along with US Box, Power Box and the thing that Tiga's have.
Welcome to the "Standard" windsurfing age.

thanks a lot, i think my new board has a powerbox.

S
Hi Seademon,
Some manufacturers like 'Select' make a fin where you can interchange the top or box fitting to suit whatever box you have on your board. I had one of their weed fins. This is quite clever - you take out two screws and interchange heads - this may be useful also if you have two boards with different boxes and thereby can use the one fin between them. The negative being that theyre not super quick to change over so you do lose interest in doing so.
Cheers!