The FC/APC to FC/APC Simplex Singlemode Big D Metal Fiber Optic Adapter Without Flange is a high-precision coupler designed for reliable, low-loss interconnection between two FC/APC singlemode connectors. With its Angled Physical Contact (APC) interface, this adapter provides ultra-low back reflection and stable optical performance, making it ideal for high-precision optical communication systems, CATV networks, and test instrumentation.