The FAMCO JVSB J Vent Shake Base – Galvanized – Roof Vent. The JVSB has an oversized base typically used on shake style roofs. Great for attic (static) ventilation and can be used with most roofing materials. A great all around attic vent. It provides a low silhouette and is open on two sides for better air flow. It helps elimate moisture and heat build-up. This roof vent works best when used with soffit or gable end venting. Built in 1/8 inch screen. Quality constructed in heavy duty 28 or 26 Galvanize steel. The FAMCO JVSB J Vent Shake Base – Galvanized – Roof Vent come in a range of diameters: 3 inch, 4 inch, 5 inch, 6 inch, 7 inch, 8 inch, 10 inch, 12 inch, and 14 inch. The FAMCO JVSB J Vent Shake Base – Galvanized – Roof Vent is manufactured by FAMCO in the United States and comes with a 1-year warranty against product defects and workmanship. If you have any questions about this product or available variations, please refer to the FAQs above or feel free to contact us by phone or email.