The 1515941-2 is a ferrule kit designed for TE Connectivity's PRO BEAM Sr. series of ruggedized expanded beam fiber optic connectors. It is specifically engineered for singlemode (SM) applications and features a precise 126 μm fiber hole size. This kit is a critical component for assembling 2 and 4 channel PRO BEAM Sr. connector inserts. When used within the PRO BEAM Sr. system, these ferrules contribute to a connection with a typical singlemode insertion loss of 0.8 dB and an operational temperature range of -40°C to +85°C. This makes the ferrule kit essential for building reliable, high-performance fiber optic links in harsh environments such as military, marine, and industrial settings.