Stokes Bluebird House Package with "T" Post Adapters Kit Includes 4 Stokes Bluebird Houses, 4 "T" Post Mounting Adapters, and 4 Blowfly Screens. The Stokes Bluebird Houses feature a 1.5" diameter entry hole and predator guard. Songbird Essentials Bluebird Nest Lift and Blowfly Screens helps keep fledglings safe. Mount the houses to your "T" posts (not included), using the included S&K T Post Mounting Adapters.