Made to the British Trust for Ornithology design. 

​​​These boxes are available with 25mm, 28mm and 32mm entrance holes.  Choose the entrance hole size based on the species you would like to attract/deter. If you have no preference, choose a box with a 32mm hole, which suits the widest variety of species.

The 25mm entrance hole is suitable for blue tits, coal tits, treecreepers, tree sparrows and other very small birds.

The 28mm entrance hole is suitable for blue tits, coal tits, tree sparrow, great tits and other small birds.

The 32mm entrance hole is suitable for all common, small-hole nesting birds including blue tit, coal tit, treecreeper, tree sparrow, great tit, pied flycatcher, nuthatch and house sparrow.
 
 
All of the boxes have:
Drainage holes in the base to prevent waterlogging.
Deep box with a high entrance hole to reduce predation.
Long roof overhang to make it difficult for predators to reach into the box whilst sitting on the roof.
Roofing felt which protects the box from the weather, making it last much longer.
Exterior painted with non-toxic, low-VOC preservative, available in a selection of colours.
 
The boxes measure approximately 30cm/12" (H), 14cm/5.75" (W) and 23cm/9" (D).