Climber taps are mainly a balance exercise that works your core and muscle groups that aid stability. It's a speed exercise so the faster you can do it the better you get at it and the more it works for you. 

What's involved: Shoulders, abs, lower abs, front hip flexors, core, adductors. 

Powered by: Lower abs and front hip flexors. 

Tip: Make it faster and you have found yourself a truly challenging exercise.