Wordpress custom metabox

<?php
// Add the Meta Box
function add_custom_meta_box() {
    add_meta_box(
		'custom_meta_box', // $id
		'Custom Meta Box', // $title
		'show_custom_meta_box', // $callback
		'event', // $page
		'normal', // $context
		'high'); // $priority
}
add_action('add_meta_boxes', 'add_custom_meta_box');

// Field Array
$prefix = 'custom_';
$custom_meta_fields = array(


	array(
		'label'	=> 'Post List',
		'desc'	=> 'A description for the field.',
		'id'	=>  $prefix.'post_id',
		'type'	=> 'post_list',
		'post_type' => array('customer')
	)

);

// The Callback
function show_custom_meta_box() {
	global $custom_meta_fields, $post;
	// Use nonce for verification
	echo '<input type="hidden" name="custom_meta_box_nonce" value="'.wp_create_nonce(basename(__FILE__)).'" />';

	// Begin the field table and loop
	echo '<table class="form-table">';
	foreach ($custom_meta_fields as $field) {
		// get value of this field if it exists for this post
		$meta = get_post_meta($post->ID, $field['id'], true);
		// begin a table row with
		echo '<tr>
				<th><label for="'.$field['id'].'">'.$field['label'].'</label></th>
				<td>';
				switch($field['type']) {

					// post_list
					case 'post_list':
					$items = get_posts( array (
						'post_type'	=> $field['post_type'],
						'posts_per_page' => -1
					));
						echo '<select name="'.$field['id'].'" id="'.$field['id'].'">
								<option value="">Select One</option>'; // Select One
							foreach($items as $item) {
								echo '<option value="'.$item->ID.'"',$meta == $item->ID ? ' selected="selected"' : '','>'.$item->post_type.': '.$item->post_title.'</option>';
							} // end foreach
						echo '</select><br /><span class="description">'.$field['desc'].'</span>';
					break;


				} //end switch
		echo '</td></tr>';
	} // end foreach
	echo '</table>'; // end table
}

function remove_taxonomy_boxes() {
	remove_meta_box('categorydiv', 'post', 'side');
}
add_action( 'admin_menu' , 'remove_taxonomy_boxes' );

// Save the Data
function save_custom_meta($post_id) {
    global $custom_meta_fields;

	// verify nonce
	if (!wp_verify_nonce($_POST['custom_meta_box_nonce'], basename(__FILE__)))
		return $post_id;
	// check autosave
	if (defined('DOING_AUTOSAVE') && DOING_AUTOSAVE)
		return $post_id;
	// check permissions
	if ('page' == $_POST['post_type']) {
		if (!current_user_can('edit_page', $post_id))
			return $post_id;
		} elseif (!current_user_can('edit_post', $post_id)) {
			return $post_id;
	}

	// loop through fields and save the data
	foreach ($custom_meta_fields as $field) {
		if($field['type'] == 'tax_select') continue;
		$old = get_post_meta($post_id, $field['id'], true);
		$new = $_POST[$field['id']];
		if ($new && $new != $old) {
			update_post_meta($post_id, $field['id'], $new);
		} elseif ('' == $new && $old) {
			delete_post_meta($post_id, $field['id'], $old);
		}
	} // enf foreach

	// save taxonomies
	$post = get_post($post_id);
	$category = $_POST['category'];
	wp_set_object_terms( $post_id, $category, 'category' );
}
add_action('save_post', 'save_custom_meta');

?>