There are three kinds of FC fiber optic adaptors, square type, single D type and double D type, all FC fiber optic
Adaptors are with metal housing, single mode FC Fiber optic adaptors are with Zirconia sleeves, multi mode
FC fiber optic adaptors are with Bronze sleeves. All FC fiber optic adaptors are simplex. 

Feature: 
. Compliant with JIS, IEC, Bellcore. 
. Optical performance 100% factory test. 
. Ceramic or Phosphorous bronze Sleeve available. 
. Flanged or Threaded mounting hardware. 
. High precision alignment. 
. Low insertion loss. 
. Convenience and easy of handing. 
. RoHS compliant. 

Application: 
. Telecommunication networks
. CATV & LAN
. Date networks
. Passive Optical Networks
. FTTH