The secret to nesting tube success is the replaceable Bee Nester Liners. In the can are 130 liners ready to provide new, clean nesting chambers each year for the Bee Nester System (water resistant coated cardboard tube (reuseable), liner & reusable end cap). They can also be inserted into the holes of  48 & 96 Hole Wood Nesting Blocks. The Bee Nester Liner is ment to complete the Bee Nester System and should not be used with out the cardboard tube or a woodblock as this is not safe for the Mason Bee cocoons