Sometimes a drummer may hit two different crash cymbals in a kit at the same time to produce a very loud accent, usually in rock music.
Custom crash cymbals up to 28 inches (71 cm) in diameter have been used by big bands.
Crash cymbals are often the first ones in a drum set to warp and ultimately crack, due to repeated striking of the edge.
If a crack is left untreated, it will begin to follow the lathe grooves around the cymbal and could potentially spread all the way around and back to the point where it started, causing the outer portion of a cymbal to simply drop off.
This allows the cymbal to vibrate freely and for little stress to be caused on the edge or at the center hole, thus reducing the chance of a crack.