This portable pet door is a true godsend! Before getting it we were either taking turns opening and closing the door, or we just left the door open and let the air conditioner or furnace compensate for our inability to close-up our home. Since using this door, we've saved on average about $200/month in utility costs. I don't have to swat flies who come through the open door in the summertime. This door is super easy to place either alongside the screen door or within the groove of the sliding glass door. It doesn't require any hardware to install and is extremely lightweight. You just attach the velcro, pop-in the door, and brace it with the sliding door. We can also transport it from room to room, and we bring it when we travel out of town so we don't wear out our welcome. When we leave the house, we just close the sliding glass door and leave the pop up pet door in the groove of the screen door, or we use a door brace for additional security. Our old dog loves his door, and we don't have to feel guilty that he's going to stress out from not being able to go outside. This door is ingenious! Our life has been dramatically improved because of it - THANK YOU!!!!!!!!!!