function jk_add_custom_sku() { $args = array( 'label' => __( 'TC SKU', 'woocommerce' ), 'placeholder' => __( 'TC SKU', 'woocommerce' ), 'id' => 'tcsku', 'desc_tip' => true, 'description' => __( 'This SKU is for internal use only.', 'woocommerce' ), ); woocommerce_wp_text_input( $args ); } add_action( 'woocommerce_product_options_sku', 'jk_add_custom_sku' );