This ST/ST Female Simplex Fiber Optic Coupler is the perfect solution for connecting two ST/ST fiber optic patch cables. This coupler features metal housing. Adapter: MM, Metal. Sleeve: Zirconia. Dust Cap: PVC UL94 HB, Color: Black/Red. Insertion: less than or equal to 0.2dB. Durability(500 Mating): 0.2dB Max Increase. Operating Temperature: -40~+85 degree Celsius.