Stainless steel ring to protect the entrance to next boxes .

The hole is 32 mm, which is considered by bird protection organizations to be a universal size for all small birds. Suitable for example for blue tits, wood sparrows etc.

With a ring around the entrance, you partly protect against the house's residents themselves destroying it with claws and beaks over time - but most importantly you prevent squirrels, woodpeckers and other birds of prey from pecking the opening larger and thus being able to get in for eggs and young.