Retooled for 2008, inside porch support added! Now with porch supports on the inside and outside. Properly sized crescent shaped entrance holes keep Starlings out of your Martin Housing. This adjustable crescent entrance cylinder can be used to train Purple Martins who are having trouble negotiating standard 1-3/16" crescent-shaped holes. Start with the full 1-1/2" opening and work down to the 1-3/16" opening that will keep out Starlings. Takes about 2 weeks to train birds. See Tips and Information page for more information on how to train them. Installs easily in gourd or wood home with 4-1/2" hole saw or jig saw and some adhesive caulk. Adjusts from 1-1/2" down to 1-3/16" in height. Order 2 porch decks if you want them on the inside and outside.