Evaluate and Reduce the header rail. Pull the shower door closed and prolong your tape evaluate from one side to the opposite. Mark the size around the body header and use your hacksaw to cut it to measurement. Clean down the Uncooked edge employing a metallic file.[13] X Investigation resource https://www.deluxeshowerdoors.com/services/glass-shower-door-installation-in-needham-ma-deluxe-shower-doors/