This is ST fiber optic Adapter made by Homk.
Local Area Networks(LANs)
Data processing networks
Low insertional loss and back reflection loss
High prcision alignment
Choice of housing material and sleeve material
Nickel plated brass body
Telcordia, ANSI, TIA/EIA, NTT and JIS compliance.
high precision size has good compatibility
resistance to friction ceramic casing
environmental stability good
card lock plug
provide separate ST type, SC type, FC type, LC type and so on many kinds of adapter
< 0.2db typical change, 1000 time matings
-40 to +85 degree