The outer shell has been precision cut and uses an ingenious system of tabs to hold it together. This further extends the lifespan ensuring that there are no fixings holding the weatherproof shell together that could rust or degrade over time. Internally there is a removable wooden nesting chamber with drainage holes for the birds to nest in. This is made from Oriented Strand Board, which is made from flakes obtained from wood waste or from saplings thinned from forests to make space for larger trees. If you need to check or clean the box it’s simply a case of twisting the fastening at the bottom and the wooden nesting chamber slides out.Fixing to the wall is easy with three concealed mounting holes in the back of the box near the top and a further hole near the base. The easiest way (and safest if you are doing this up a ladder) to mount the box is to remove the inner, fix the outer shell onto the wall then slide the inner roost chamber back into the box and secure it in place.Features:Unique innovative bird box; recycled plastic outer shell with wooden internal nesting chambers.Each tower can accommodate three pairs of sparrows nesting together.Help the declining sparrow population by putting up one of these bird boxes designed especially for house sparrows.Fixed roof to enable the sparrow tower to be fitted right up in the eaves just where the sparrows prefer.Specifications:Material: Recycled LDPE plastic outer with internal OSB nesting chamberConstruction: Outer recycled plastic panels fitted together using integral tabbing system. Internal nesting chamber stapled together.Fixing: 3 concealed keyholes and further fixing hole at baseDimensions and WeightDimensions: Height 65cm, Width 17cm, Depth 17cm2.8kg