Add and create multiple meta boxes for a custom post type

I’m trying to save the input from the 3 meta boxes I created. Here is my code below. What am I missing since I am only saving the smashing-post-class 3 times.

/* Fire our meta box setup function on the post editor screen. */
add_action( 'add_meta_boxes', 'smashing_add_post_meta_boxes' );
add_action( 'save_post', 'smashing_save_post_class_meta', 10, 2 );


  /* Create one or more meta boxes to be displayed on the post editor screen. */
function smashing_add_post_meta_boxes() {

    // sku,price, short description
    add_meta_box(
      'smashing-post-class',      // Unique ID
      esc_html__( 'SKU', 'SKU' ),    // Title
      'smashing_post_class_meta_box',   // Callback function
      'products',         // Admin page (or post type)
      'normal',         // Context
      'default'         // Priority
    );
    add_meta_box(
        'smashing-post-class1',      // Unique ID
        esc_html__( 'Price', 'Price' ),    // Title
        'smashing_post_class_meta_box',   // Callback function
        'products',         // Admin page (or post type)
        'normal',         // Context
        'default'         // Priority
      );
      add_meta_box(
        'smashing-post-classs2',      // Unique ID
        esc_html__( 'Short Description', 'Short Description' ),    // Title
        'smashing_post_class_meta_box',   // Callback function
        'products',         // Admin page (or post type)
        'normal',         // Context
        'default'         // Priority
      );

  }


/* Display the post meta box. */
function smashing_post_class_meta_box( $post ) { ?>

    <?php wp_nonce_field( basename( __FILE__ ), 'smashing_post_class_nonce' ); ?>
  
    <p>
      <label for="smashing-post-class"><?php _e( "Add meta tag", 'example' ); ?></label>
      <br />
      <input class="widefat" type="text" name="smashing-post-class" id="smashing-post-class" value="<?php echo esc_attr( get_post_meta( $post->ID, 'smashing_post_class', true ) ); ?>" size="30" />
    </p>
    
  <?php }


/* Save the meta box’s post metadata. */
function smashing_save_post_class_meta( $post_id, $post ) {

    /* Verify the nonce before proceeding. */
    if ( !isset( $_POST['smashing_post_class_nonce'] ) || !wp_verify_nonce( $_POST['smashing_post_class_nonce'], basename( __FILE__ ) ) )
      return $post_id;
  
    /* Get the post type object. */
    $post_type = get_post_type_object( $post->post_type );
  
    /* Check if the current user has permission to edit the post. */
    if ( !current_user_can( $post_type->cap->edit_post, $post_id ) )
      return $post_id;
  
    /* Get the posted data and sanitize it for use as an HTML class. */
    $new_meta_value = ( isset( $_POST['smashing-post-class'] ) ? sanitize_html_class( $_POST['smashing-post-class'] ) : ’ );
  
    /* Get the meta key. */
    $meta_key = 'smashing_post_class';
  
    /* Get the meta value of the custom field key. */
    $meta_value = get_post_meta( $post_id, $meta_key, true );


         /* If a new meta value was added and there was no previous value, add it. */
         if ( $new_meta_value && '' == $meta_value )
         add_post_meta( $post_id, $meta_key, $new_meta_value, true );
         /* If the new meta value does not match the old value, update it. */
     elseif ( $new_meta_value && $new_meta_value != $meta_value )
         update_post_meta( $post_id, $meta_key, $new_meta_value );
         /* If there is no new meta value but an old value exists, delete it. */
     elseif ( '' == $new_meta_value && $meta_value )
         delete_post_meta( $post_id, $meta_key, $meta_value );      
 
  
  }