The switches, when installed in an electronic or digital device, are going to let you input codes and numbers easily. When you use the thumbwheel, you will be generating a binary code that matches the digit. People find that these thumbwheel switches are a way of adding reliability when it comes to numeric input.
These types of devices have been popular for quite some time, and before the advent of newer technology, they were the only way to input information into many electronic devices and computers. One of the interesting things about the thumbwheel switches is that even though there are new technologies and methods available, quite a few people are actually choosing to use the thumbwheel switches for many applications still. Why would they want this older technology? Reliability and ease of use are two of the biggest factors.