I rented the I-SAM Portable ball machine for 24 hours (for $20) and have the following to say about it: PLUSES + Great for groundstroke practice plus lobs, especially if you're trying to fix any quirks in your strokes. But it is essential to have someone knowledgeable actually observe you and make suggestions. I improved a lot in two sessions, but hurt my shoulder from practicing too long. + Did not jam with ball fuzz. There was very little fuzz inside the machine, but there was a lot outside of it. + Lasted about 6 hours total, but I did charge it overnight after initially using it for 2 hours. + The fuse on the back popped out when a ball got stuck. This is a good thing if you ever try to stick a hand in there, but you're REALLY NOT supposed to. I was being dumb. I didn't know that you just have to turn it back on and it would feed the stuck ball. + Holds up to 250 balls. I had around 100 balls, and it took about 15 minutes to feed these with the feed setting at 4. + Does not start feeding right away. You have enough time to get to the other side of the court. MINUSES - A bit heavy to lug around, especially if you have to walk far and you're already carrying a tennis bag and a ball hopper full of balls. It has no wheels. - The oscillation feature was challenging to set. I placed it at the baseline, in the middle, and had to carefully adjust the angle so the balls wouldn't go off court. But maybe I just needed to read the manual. - Sometimes the feed rate was not consistent. It would get stuck, then would feed you eventually. So sometimes you would stand there longer, waiting for the ball. - Perhaps a bit too tall to fit in the trunk of a small car. But fits easily in the backseat. - This being a ball machine, the feeds were a little too consistent. IMHO it's still best to have a partner feed you balls for practice. WOULD I BUY THIS MACHINE? Not right away. I would make sure to try other brands first. WOULD I RENT THIS MACHINE AGAIN? Maybe one more time. Then I'd go back to regular play and partner drills.