I just got a set of Axxis Ultimate brake pads. My helms says to put the shim thats on the brake pads back on. I know this is where the anti squeel goes, but problem is one set of the brake pads were stolen So I only have one shim, is it needed, and whats its purpose, is it just to reduce brake squeel, or can I do without it.

 

You can do without them, it's to reduce brake squeal.