Wrens are the least fussy of house birds and these big bug eaters are great to have around. The 1 1/4" hole is within the acceptable range for all types of wrens. They prefer their house 6-10' from the ground in mixed wooded areas. The thick walls and roof are good insulation and birds appreciate unfinished wood, no stains and no paints. Each house is designed so the bottom can be easily removed by 2 screws for annual cleaning. Made from reclaimed wood from old New England mills or salvaged barns. Made by a local crafter for Real Green Goods. Approximately 9" tall x 7" wide by 7" deep, including the 2" overhang.