Our woodstone® range of nest boxes have been designed and developed as part of our professional vivara pro range. Unlike a traditional wooden nest box, these boxes will not rot away or deteriorate. Every woodstone® nest box from cj wildlife is guaranteed for 10 years. Constructed from a mix of concrete and wood fibres, woodstone® nest boxes safeguard against attacks from predators including woodpeckers, cats and squirrels. The material insulates the nest which creates a more consistent internal temperature than an ordinary wooden box. This is especially important during the breeding season and ensures that young birds have a greater chance of survival. We recommend building this into a wall. House sparrows prefer to nest in groups or colonies, so this nest box has been designed with 2 chambers to allow them to breed in close proximity. Approx. Weight 7kg