We took our signature #1-selling shingle, Timberline HD®, and transformed it by strengthening the common bond and creating the industry's largest nailing zone. Timberline® HDZ Shingles have the same renowned Timberline quality and performance you know and love, with improved nailing accuracy and installation efficiency! Timberline® HDZ Shingles are easy and fast to install, with an incredible 99.9% nail placement accuracy! The StainGuard Plus Algae Protection Limited Warranty* protects your roof investment with GAF Time-Release Algae-Fighting Technology. It's algae resistance so powerful it allows us to offer a 25-year limited warranty against blue-green algae discoloration on many of our most popular products.* (Applies only to shingles with StainGuard Plus labeled packaging).