I bought a Fender P-Bass yesterday and would like to put flats on it. Because of money constraints I can only really afford to buy them from Best Buy(yay for giftcards). While looking through the selection, I found a lot of the brands that people have talked about on here, but the kinds on there are "signature series". Is that typically a custom gague? Also, should I be looking for Long or Short scale, and what is the difference between them?