CoreBluetooth limitations?

Question

I can't find any mention of the limitations on CoreBluetooth framework's read/write. Does anyone know what the speed & size limitations of these two functions are?

-(void) writeValue:(int)serviceUUID characteristicUUID:(int)characteristicUUID p:(CBPeripheral *)p data:(NSData *)data

-(void) readValue: (int)serviceUUID characteristicUUID:(int)characteristicUUID p:(CBPeripheral *)p

I need to know what the maximum size for data is and at what speed and how fast we can use these functions.

Thanks in advance for any help.

Sia