Violet-green Swallow nest-box. These are wooden boxes made by Countryside Culture of Grants Pass, Oregon. Metal roof, either Red or Green. (Please specify in Comments section) Hinge and pivot for easy cleaning. These boxes have a slot hole 7/8 inches high and are thus intended to be House Sparrow resistant. Whether they are or not may depend on whether the House Sparrows in your area take special seminars taught by House Sparrow Houdini-types on how to get into Swallow boxes. This hole size was successful for both of our families in the 2009 season for us on Beacon Hill in Seattle, WA. Best placement for Violet-greens is high up under eaves. For Tree Swallows, placing the box on a tree near wetlands or lake margins could work. There is anecdotal reason to think that Violet-green Swallows may be desperate for housing in many areas of the urbanizing West, so your local Violet-green Swallows may be very appreciative.