This keystone SC coupler is purpose-built for single-mode OS2 applications where low back reflection and superior return loss are essential. The APC angled polish reduces Fresnel reflections and improves signal stability in reflection-sensitive systems such as FTTH distribution, CATV networks, and precise telecom links. The green housing provides clear visual identification of APC compatibility to prevent accidental UPC/APC mismatches during deployment. A zirconia ceramic ferrule sleeve ensures precise mechanical alignment and long-term durability across many mating cycles. Designed for standard keystone plates and patch panels, this adapter delivers consistent optical contact, reliable mechanical retention, and professional-grade performance for demanding single-mode installations.