I’ve never had/seen one, but I doubt they’re bult very well, or work well enough for you to ever find out they’re not built very well. The whole point of the thing is to be way cheaper than the low-end $250 full-size models.
Also I doubt anything that small would work well: I weigh ~270, and the one I have uses some variation of automobile gas-filled shock absorbers as the rams. After about 15 minutes the rams are too hot to touch, and are too “loose” for me to continue, so I have to do my exercising ~10 minutes at a time.
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It’s kind of like the exercise cycles: a Bally LifeCycle costs $1400, but there’s cheap $79 ones at Wal-Mart. The $79 ones are the ones you always see sitting out by the trash on trash day, because they simply don’t work very well.
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My M-I-L has one. She’s about 120# and it works for her but I don’t think I would recommend it. They are simply not built well and stability is a real issue. If you’re not careful, you can lose your balance and find yourself with a MiniStepper where you may not want it!