I bought my first electric guitar (Yamaha Pacifica) from a chap on gumtree for 50 quid the other day, and have cleaned it up and put some new strings on - it looked like it had been stored away for years, so plastics are a bit mellow yellow. When I took off the back cover, I noticed that it had 2 tremolo springs, but with sockets for a few more springs.

I was just wondering - are these springs a standard size, and why would you have more or less springs - does it make a difference?