One-way mirrored panel lets you see the birds up-close and they can't see you. Designed to sit inside the house, this feeder is easy to install. With the unique dove-tailed mahogany side panels, simply place the feeder on the windowsill and slide the panels out to fit the window. The one-inch thick side panels provide great insulation and security. It's easy to fill and clean from inside your home. Feeder fits most double hung windows from 26 to 36 inches wide.