Discounted Duraflow 50 & 75 Roof Vents Colours come in Grey, Brown, and Black. Bundle deals are as follows. Duraflow 50 - vents 200 sq.ft. of attic space Individually@$8.00 3 to 10@$7.50 10+@$7.00 Duarflow 75 - vents 300 sq.ft. of attic space Individually@$12.50 3 to 10@$12.00 10+ @$11.50