Hi, I did a search and also read through the two stickies for replacing brake pads (a huge help BTW) and didn't see any mention of this. I put new pads on one rear tire, using the shim that came with the new pads. Once I got the wheel back on, I pulled the old shim off the used pad and there was another shim underneath that had slots or vents if you will. Do I need to use two shims or is the one that came with the part good enough. I would hate to have to pull the wheel to put the shim in. Looking through the stickies, I didn't see where the authors used two shims. Thanks!