Attach this birdhouse to your window and watch the nesting process from close range. 1-1/4" opening is appropriate for many backyard species. The suction cups provide for stable mounting. Simply install the house, close the curtains and periodically observe nest building, egg laying and chick hatching from within your home. Hand crafted in Maine of sustainably grown Eastern White Pine. Repair or replacement of any defects in manufacturing or materials upon return of any defective item to Coveside Conservation Products.