Two times - immediately - change and then refund because it was completely useless - it was hitting even on my own body.
I wonder how a well-known company releases such a machine.
Stay away.

The most expensive piece from Bosh and the most unreliable. I changed it 3 times at the company because objectively it didn't work and it hit like a clown at his wedding! Money wasted! After 3 replacements and after they talked to me as if they were doing me a favor, Bosh informed me that I just keep it even if it doesn't work! The cheaper ones are more reliable!