The spring clip keeps pressure/tension on the pad while it rides in the caliper. It helps to reduce noise and keep the pads aligned so you dont have odd ball wear on them. Like Empire stated they are worth the 9 bucks they cost, especially if this is your daily.

A side note for anyone doing any kind of brake swap. Making sure your brakes are equipped the way they came from the factory is much more important than what color you powder coat them. Spend your hard earned cash wisely. Dont cheap out on hardware they came with just for the sake of them being pretty red. Thats so "Honda". Eh.