Astria 10 Pack Through Wall Shield SV4.5TWSK10 Buker Pond, Maine Stock Photo Alamy. Astria 10 Pack Through Wall Shield SV4. 5TWSK10 Product Details What advantages does the Astria 10 Pack Through Wall Shield provide in a direct vent system, especially regarding weatherproofing and ensuring a secure installation? The Astria 10 Pack Through Wall Shield offers significant advantages in a direct vent system, particularly in weatherproofing and secure installation. These shields create a protective barrier around the vent pipes as they pass through walls, effectively preventing water infiltration and air leaks. This weatherproofing is crucial for maintaining the system's efficiency and preventing potential damage from moisture. Additionally, the shields ensure a secure fit, enhancing stability and alignment during installation. Their durable construction contributes to long term reliability and compliance with building codes, making them essential for safe and efficient venting. Note: This unit requires venting pipe with an inner diameter of 4. 5 Inches. Please see the Venting Components section on this page for the venting pipe that must be used with this unit. Features for Astria 10 Pack Through Wall Shield SV4. 5TWSK10 Durable galvanized steel construction Use to maintain the proper clearance when passing the pipe through a combustible wall Secure locking tabs Measures 13 inches long