Leaf Filter, Then MasterShield. In 2001, a struggling roofing and siding contractor invented the world's first micromesh gutter guard. His name was Alex Higginbotham. Alex also taught himself to write patents. In 2003 he was awarded a patent on his invention. His patent was US6,598,352 and he named his invention LeafFilter®. It was the best gutter guard anyone had ever seen. Nobody could believe a gutter cover could work so well. Except Alex. Who was already working on another groundbreaking patent: US7,191,564. LeafFilter®+ US7,191,564 = MasterShield. MasterShield. Multi-Patented. The most advanced gutter protection system available. For more information on Alex Higginbotham's revolutionary gutter guards visit MasterShield.com.