https://www.callupcontact.com/b/businessprofile/Stay_Dry_Roofing/9941495">https://www.callupcontact.com/b/businessprofile/Stay_Dry_Roofing/9941495. A quality roofing system will have them mounted throughout the side of https://nelsonosna502081.ltfblog.com/38089489/facts-about-stay-dry-roofing-revealed