I am getting some of these swivels from BPS but i dont know what size to get because im not sure what the number for the size means. If anyone can tell me how to figure this out i would really appreciate it. Thanks!

Here is the link the the swivels i am getting http://www.basspro.com/servlet/catalog.TextId?hvarTextId=7817&hvarTarget=search&cmCat=SearchResults

The smaller the number the bigger the swivel. So 12 would be the smallest, and the 2/0 would be the biggest. 2/0 is way to big for anything except sea fishing(I would think). I'm going to say go with something like an 8 or 10, but dont take my word on that. Its just like hooks.

Mike about nailed it.  Go with something a little smaller.  I normally try and use the smallest one I can get away with.  I am actually trying to get away from using them as much as I can but they come in handy under a few circumstances and they just make changing lures so much easier.  

7's or 8's is what I usually use. But, like Mike said, you can go smaller like 10s.

Well im going to use them on the blades for when i make spinnnerbaits, so what size should i get for that.

I like to go really small, never had a problem with it.  Just make sure you don't get too big.

Hey that is a bad loure to use don't use it ever!!!!!!!

Swivels can save a lot of trouble from line twist. If you're using inline spinners, spoons, pre-rigged worms, or any other lure that spins, a swivel is a must. They are also the best thing to use for carolina or lindy rigs, keeping the weight from sliding down. I'm not quite sure but I think that different sized swivels can handle different wieght, the bigger obviously capable of pulling more pounds.

I use size 10 and 8 swivels, i agree with what danarchy said.