So-called Liebig-Einfachbeute, coated with walnut oil - hoping that walnut oil is a good compromise between water protection and breathability. Boiled linseed oil, in the experience of other beekeepers, often hinders breathing and therefore increases risk of mould. Apart from that, it contains heavy metal salts and I really don’t want them in my honey.
Walnut oil is not as durable, which is a definitive disadvantage. But as long as I only have to re-coat the wood on a yearly basis, I would be OK with that.