The SCI-4 and SCI-6 faceplates are designed to be used with the SPA-400 stereo intercom system. These faceplates are 2.25 inches in diameter and have a round shape. They are made of high-quality materials and are designed to be durable and long-lasting. These faceplates are an important component of the SPA-400 intercom system, as they provide a user interface for controlling the intercom’s functions. They are easy to install and use, making them a convenient and practical choice for pilots who need a reliable intercom system.