public static function addComboGroupItemsDownloadColCheckbox($chk_pro) {
        ?>
        <label for="chk_pro[combo_set]">
            <input
                type="checkbox"
                class="check_pro check_product"
                id="chk_pro[combo_set]"
                value="combo_set"
                <?php usces_checked($chk_pro, 'combo_set'); ?> />
            <?php esc_html_e('Combo-Set Selections', 'wcexics'); ?>
        </label>
        <?php
    }