This is an excellent starter kit to attract native pollinators to you backyard. It comes fully assembled with 30 unpopulated sphagnum mason bee reeds that mason bees prefer over any other kind of nest. It is ideal for placing under the eaves of a house or barn. Made of high grade sustainably harvested cedar (FSC certified),the nest box is naturally moisture resistant. the starter reeds sit will back inside the nest, giving them excellent weather protection. You can start this with some purchased mason bees, but you might want to see what native pollinators come to this nest. The sphagnum reeds are highly attractive to mason bees and other native pollinators.