public SkiPass getDaysSkiPass(int numDays) {
        if (numDays <= 0) {
            throw new IllegalArgumentException("Cannot create card for non-positive number of days");
        }

        Calendar calendar = new GregorianCalendar();
        Date activationDate = calendar.getTime();
        calendar.add(Calendar.DAY_OF_YEAR, numDays);
        Date expirationDate = calendar.getTime();

        return system.createSkiPass("HOURLY", activationDate, expirationDate, 0);
    }