This Square D 9999SX11 87972 N.O. Electrical Interlock is a high-quality switch accessory that is made in the United States. It is designed for use with electrical equipment and is perfect for businesses and industrial applications. The interlock is compatible with Square D products and is sold as a single unit. The package includes one interlock, and it is brand new. This item is perfect for those who need a reliable interlock for their electrical equipment. It is important to note that this product is not refurbished or used. Buy with confidence knowing that you are getting a brand new product.