Bat boxes generally need to be warm in summer for rearing young and cooler in the winter for hibernation. Greenkey boxes are designed to be draught proof.The natural timber is both easthetically attractive and resistant to all weathers.The timber is untreated internally as some chemicals can harm bats.The bats that use a bat box are species that favour living in crevices and tight spaces, so the entrance slit reflects the size. (20mm)Medium Bat Box.Dimensions: 14cm x 8cm x 28cm approxGrooved bat ladderEntrance slit 20mmPicture image for display purposes only. Boxes do not come with Bat images.Each bat box is sold individually.