This nest box made from wood has a galvanised roof for added protection against the elements. The 30mm hole with added metal ring to protect from squirrels is a perfect size for Wrens, Blue tits, Coal tits and similar sized box nesting birds. Door access to the side for easy cleaning. The wooden box can be painted or varnished for lasting protection, but we do recommend using a pet safe water based product. Made from FSC certified timber.