CRS stands for Cymbal Resonance System.
CRS isolates your cymbal from your cymbal stand - in short. The result is, as you may know from RIMS*, that your cymbals sounds more open and moves more freely.
Your cymbals also feels a little different to play on when using the CRS holder. This is because the cymbal can move freely in the CRS holder, and it therefore feels a little "less dead" to play into - which is very comfortable too.
CRS is born with a wing nut and two felt discs.
Note: We have not been successful in mounting No Nuts Cymbal Sleeves on the CRS system yet.
To give you a better understanding of what CRS can contribute with, you can try listening to a cymbal while holding it with your index finger. Then try putting the cymbal back on your cymbal stand - and hear the difference.
With CRS, you get just that open sound and feel from your index finger, just on your cymbal stands.
If you have mounted a tambourine and a woodblock on the same stand, the tambourine will play happily when you play on the woodblock. However, if you use CRS to hold your woodblock, you reduce the tambourine's "rattling along" very significantly.
The same principle applies if you have a splash cymbal mounted on your bass drum. Then it will probably play along when you play the bass drum. Here, too, CRS can help, and by having your splash cymbal mounted with CRS, you can reduce the vibrations from the bass drum, causing your splash to sing along.
* RIMS is a system for holding the toms using small rubber rings. These isolate the drum from the hardware, and the drum can thus sound and move freely. The concept is a bit the same with CRS - hence the comparison.