The stair climber is a piece of cardio equipment that simulates climbing stairs. It is less common in public gym than treadmills, stationary bikes, and elipticals. These machines allow you to change the difficulty of the workout by increasing or decreasing the speed of the steps. Most of them also have handles that you can hold on to that will track your heart rate. Another way to make this machine more difficult is by wearing a weighted vest. Firefighters often use this machine while wearing their bunker gear in order to test their endurance.