The Air Brake Repair Diaphragm #HD30D is a new, high-quality replacement part designed for T-30 size trucks with an 8 " diameter and 1 1/2" height. Manufactured by an unknown manufacturer, this diaphragm unit is guaranteed to provide reliable and efficient performance for your commercial truck. Whether you need to repair or replace your existing diaphragm, this product ensures a proper fit and optimal functionality for your vehicle.