{TAIL ~ The ventilation system} includes {HEAD ~ a stub venting tube} that together with a throughbore in the lower floor allow the modularly stackable centrally ventilated bird houses to be stacked, four lower compartments, four lower dowels, four upper compartments, four upper dowels, and a vent cap 
{ TAIL ~ The ventilation system } includes { HEAD ~ a stub venting tube } that together with a throughbore in the lower floor allow the modularly stackable centrally ventilated bird houses to be stacked , four lower compartments , four lower dowels , four upper compartments , four upper dowels , and a vent cap
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