Sogeman Microlog MD4077 Bugbusters companionway insects screen, 40" wide X 77" long, 100% Mil Spec Polyester mesh that is flame retardant, lead ballasted (will not affect compass) and has built-in ties. These screens are a simple solution for no-see-ums, mosquitos and other bugs.
Installation is a cinch, just put the Bugbusters over the cockpit opening and the generous dimensions allow easy access to and from the cockpit and maximum ventilation. To order the correct size screen, measure the maximum inside measurement from forward of companionway to bottom and add 2 - 3 inches. Then take width outside companionway sides and add height of sides over the roof to get width of screen.