Be careful when buying this product. It's not a standard plastic cover that fits any stand. It's not. It's specifically for the 600 sonor series stand, and for that, is the best. It's made of a very good quality plastic which hardly deteriorates with time. I've been using it for over a year and it doesn't show any sign of ageing.
These plastic covers do their job perfectly. Prevent any friction from metal on metal and protect your cymbals really well. Seem to be made to a high standard. Not, you will need to use washers for these to function properly.