public static function getPlayButton($classes = array())
    {
        $classes = array_merge(array('readspeaker-play-button'), $classes);
        $classes = apply_filters('ReadSpeakerHelper/play_button_class', $classes);
        $classes = implode(' ', $classes);

        $playButton = '<div class="rsbtn rs_skip rs_preserve"><a id="' . self::$playButtonId . '" href="//app-eu.readspeaker.com/cgi-bin/rsent?customerid=' . self::$customerId . '&amp;lang=' .get_locale(). '&amp;readid=' . self::$readWrapperId . '&amp;url=' . self::currentUrl() . '" class="' . $classes . '">' . __('Listen', 'readspeaker-helper') . '</a></div>';

        return apply_filters('ReadSpeakerPlayer/play_button', $playButton);
    }