Swivel plastic base is easy to break what happened
Second may be the landlord to buy chairs, the quality is not very good, the quality of plastic things are very different, some material strength is good the price is very expensive, some general strength of materials price is very general; in addition, after all, plastic plastic, plastic is not what our civil aviation god seven engineering plastics, and also not strong where to go, or be careful to use the drop...
In my humble opinion, the first may be the landlord weight alarming, plastic base general chair cannot reach so high stress range
