I bought these castor cups to isolate a grand piano from the floor in my very poorly soundproofed Nashville apartment. The build quality of the cups is very good, as it should be at this price point. I have rated them 4 stars as I believe the isolation from the floor could be a little better in the bass end - I have almost total isolation from mid to high range and roughly 50 to 70 percent reduction in transmission of low mid to extreme lows.
Delivery to the USA was fast - only about one week with good tracking updates.
In terms of the packaging, the box was badly damaged and given the size of the holes in it I am very lucky that all three castor cups arrived - however, they did and in perfect condition.