Double pedal

When you buy a drum kit, it usually has a simple pedal to play the kick like this:

My drum kit obviously had one when I bought it. I've practised a lot with it and I'm quite pleased with the result.
Heavy metal and hard rock bands have a drummer who uses a different pedal to be able to play faster. Today, my new drum teacher brought one of these pedals to the class. It name is "Double pedal", look a picture:

 I'm rather advanced in rhythms with single pedal, but I have no experience with one of these wonders. I was surprised, I'd always wanted to play the kick with one and today I've done it. I've enjoyed like a little kid.
After mounting it, my teacher showed me a book to practise with double pedal from the beginning. I've tried during little time and then he told me that I could do what I want, I could practise any rhythm I want or any song I listen! Great! It has been a wonderful although short experience, but I was happy. Also, the pedal I've tried is a very good and expensive pedal, so better.

In the end of the class, my teacher told me, he's going to bring the pedal to the next class too. I'll wait...!