@Override
    public String calculateTimeOnlyPattern() {
        if (timeOnlyPattern == null) {
            String separator = getTimeSeparator();
            boolean ampm = "12".equals(getHourFormat());
            timeOnlyPattern = ampm ? "hh" : "HH";
            timeOnlyPattern += (separator + "mm");
            if (isShowSeconds() || isShowMilliseconds()) {
                timeOnlyPattern += (separator + "ss");
            }
            if (isShowMilliseconds()) {
                String fractSeparator = getFractionSeparator();
                timeOnlyPattern += (fractSeparator + "SSS");
            }
            if (ampm) {
                timeOnlyPattern += " a";
            }
        }
        return timeOnlyPattern;
    }
Standard 576px considered a small screen so we can auto switch the picker to touch mode
primefaces/src/main/java/org/primefaces/component/datepicker/DatePickerBase.java