Landmark Impact Resistant (IR) shingles reflect the same high manufacturing standards and superior protection as the rest of CertainTeed's line of roofing products, and they meet UL 2218 Class 4 Impact Resistance at time of manufacture. Landmark IR shingles are built on the industry's toughest fiber glass mat base, and have an added durable reinforcement on its underside to achieve the highest (Class 4) impact resistance. Complex granule color blends and subtle shadow lines produce a distinctive color selection. This product also features CertainTeed's NailTrak that offers a wider nailing area. Landmark IR shingles are algae resistant, and help protect against staining or discoloration caused by algae.