Astria 12-inch HT Offset and 8-inch HT Return 30E-12HTO-8HTRAstria 12 inch HT Offset and 8 inch HT Return 30E 12HTO 8HTR Product Details What is the function of the Astria 12 inch HT Offset and 8 inch HT Return, and how do they help redirect chimney pipes while maintaining proper ventilation in high temperature chimney systems? The Astria 12 inch HT Offset and 8 inch HT Return are designed to help redirect chimney pipes in high temperature chimney systems. Their primary function is to adjust the direction of