t seems that normally you need a 16mhz crystal, and two 22pf caps, but the pro mini doesn't seem to have the caps. Can someone please tell me about this smd crystal?
They're using a resonator instead of a crystal...basically it has the caps built in. 2 pins go to the regular chip clock connections, the 3rd pin goes to ground. As spycatcher2k says, they're not as accurate as crystals.
...it has 4 pads....
If you look at the data sheet you'll see that 2 of the pads on SparkFun's SMD crystal are just for anchoring -- the crystal itself is on pins 1 & 3.
If you're interested in a SMD crystal, here's the one I've been using:
Good luck!