Promo and Font Icon changing by users CMB

Promo font awesome icon easily changing by users
// example-function.php

$meta_boxes['test_metabox'] = array(
        'id'         => 'test_metabox',
        'title'      => __( 'Font Awesome', 'cmb' ),
        'pages'      => array( 'acme_product', ), // Post type
        'context'    => 'normal',
        'priority'   => 'high',
        'show_names' => true, // Show field names on the left
        // 'cmb_styles' => true, // Enqueue the CMB stylesheet on the frontend
        'fields'     => array(
            array(
                'name'       => __( 'Font Awesome', 'cmb' ),
                'desc'       => __( 'write your icon name', 'cmb' ),
                'id'         =>'promo-icon',
                'type'       => 'text',
                'show_on_cb' => 'cmb_test_text_show_on_cb', // function should return a bool value
                // 'sanitization_cb' => 'my_custom_sanitization', // custom sanitization callback parameter
                // 'escape_cb'       => 'my_custom_escaping',  // custom escaping callback parameter
                // 'on_front'        => false, // Optionally designate a field to wp-admin only
                // 'repeatable'      => true,
            ),







// custom post promos (custom-post.php)

function create_post_type() {
  register_post_type( 'acme_product',
    array(
      'labels' => array(
        'name' => __( 'Products' ),
        'singular_name' => __( 'Product' ),
        'add_new'=>_('Add New product')
      ),
      'public' => true,
      'has_archive' => true,
      'rewrite'=> array( 'slug' => 'product' ),
      'supports'=> array( 'title', 'editor', 'custom-fields', 'author', 'comments', '' )
    )
  );
}
add_action( 'init', 'create_post_type' );


// From html page

        <div class="promo_content_area fix">
            <div class="container">
                <div class="row">
                        <?php
                        global $post;
                        $args = array( 'posts_per_page' => 4, 'post_type'=> 'acme_product');
                        $myposts = get_posts( $args );
                        foreach( $myposts as $post ) : setup_postdata($post); ?>
                        <?php
                        $promo_icon = get_post_meta( $post->ID, 'promo-icon', true );
                        ?>
                        <div class="col-md-3">
                        <div class="promo_content">
                            <?php if($promo_icon):?>
                            <i class="fa fa-<?php echo $promo_icon;?> icon-all"></i>
                            <?php else:?>
                                <i class="fa fa-home icon-all"></i>
                            <?php endif;?>

                            <h2><?php the_title();?></h2>
                            <?php the_content();?>
                        </div>
                        </div>
                        <?php endforeach;?>
                </div>
            </div>
        </div>





// have to show in (functions.php)


include_once('inc/custom-posts.php');


// Initialize the metabox class

function be_initialize_cmb_meta_boxes() {
    if ( !class_exists( 'cmb_Meta_Box' ) ) {
        require_once( 'inc/cmb/init.php' );
    }
}
add_action( 'init', 'be_initialize_cmb_meta_boxes', 9999 );


include_once('inc/cmb/example-functions.php');