title: Meta box image field size
body: <p>I'm using Custom metaboxes and fields for Wordpress and I have added image field.</p>
  
  <p>At the frontend I can print image, but I'm not able to add apply image size for it.</p>
  
  <p>In my module I have set CMB field:</p>
  
  <pre><code>array(
      'name' =&gt; __('Image', 'cmb'),
      'desc' =&gt; __('Upload an image or enter a URL.', 'cmb'),
      'id' =&gt; $prefix.
      'image',
      'type' =&gt; 'file',
      'allow' =&gt; array('url', 'attachment'),
  ),
  </code></pre>
  
  <p>For testing in single.php file I have:</p>
  
  <pre><code>global $post;
  $image = get_post_meta($post-&gt;ID, "_cmb_image", true); 
  </code></pre>
  
  <p>This works for printing image in full size:</p>
  
  <pre><code>&lt;img src="&lt;?php echo $image; ?&gt;" alt="" /&gt; 
  </code></pre>
  
  <p>I have tried different ways to print image in certain size which is set in theme functions.php.</p>
  
  <p>For example tried this:</p>
  
  <pre><code>&lt;?php echo wp_get_attachment_image( get_post_meta( get_the_id(), '_cmb_image', true ), 'thumbnail', false, array( 'class' =&gt; 'vert-align-mid' ) ); ?&gt;
  </code></pre>
  
  <p>And this: </p>
  
  <pre><code>&lt;?php echo wp_get_attachment_image( $image, 'thumbnail' ); ?&gt;
  </code></pre>
  
  <p>This aren't working and I'm getting empty value. Any help how to print image in custom size?</p>