Product Summary SKU Name is a block exported by the Product Summary app responsible for rendering the selected SKU's name.

1. Import the vtex.product-summary app to your theme's dependencies in the manifest.json:

  "dependencies": {
    "vtex.product-summary": "2.x"
  }

2. Add the product-summary-sku-name block to your store theme as a child of product-summary.shelf. For example:

   "product-summary.shelf": {
    "children": [
      "product-summary-image",
      "product-summary-name",
+     "product-summary-sku-name",
      "product-summary-attachment-list",
      "product-summary-space",
      "product-summary-column#1"
    ]
  },

To apply CSS customizations in this and other blocks, follow the Using CSS Handles for store customization guide.