The KidCo Gateway 5.5" Extension is designed to work with both the KidCo Center Gateway and the KidCo Gateway, pressure-mounted gates that install quickly and do not damage walls. One extension can be added for an opening 37 1/4" to 42 3/4". Two extensions can be added for an opening of 42 1/2" to 48". No more that two optional extension kits per gate are recommended. Constructed of strong tubular steel and 29 1/2" tall, it's great for kids and pets.