Really great, so I had imagined.
For material:
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The material I would describe with hard rubber. Contrary to other allegations.
Assembly:
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Slightly awkward to get these things under the feet of the machine. But that has to do nothing with the parts themselves. Does make you feel even less, the vibrations are gone. But I would min. 2 people recommend.
Volume:
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For volume, one can say that only accept these parts the vibration noise. Does anyone have however problems with the noises generally, it would be better to buy a quieter machine.
Conclusion:
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I would buy these things at any time again, the money is worth it in any case.