Didn't realize this, but this company invented the "spinning-wheel" ball machine that has been copied by everyone else (in fact, they even make ball machines for other companies like Wilson). I needed to mod my Tennis Tower and they told me to come in and they'd do it free of charge. I came in and found extremely helpful and friendly staff, and they modded the machine while I had lunch. If you're in the market for a home unit or a portable, don't hesitate to call on Sports Tutor. They really are the BEST!!!