@Override
 public void writeToNBT(NBTTagCompound compound) {
   compound.setBoolean(KEY_IS_ACTIVE, isActive);
   super.writeToNBT(compound);
 }
 @Override
 public void readFromNBT(NBTTagCompound compound) {
   super.readFromNBT(compound);
   isActive = compound.getBoolean(KEY_IS_ACTIVE);
 }