Nesting boxes with plastic insert from OESIEG : • Size: 25 x 20 x 25cm (H x W x D) • With plastic insert The wooden concave can be replaced with a cardboard insert after all the young birds have hatched. During regular cleaning of the nesting box, the cardboard insert is discarded and replaced with a new one. This ensures that the nesting box is always clean, yet can still be cleaned easily and efficiently.