... typeF6-21B4 10/100Mbps with four twist-pair ports and backup optic port, managed typeF6-20B4 10/100Mbps with four twist ... -pair ports and backup optic port, unmanaged typeF6-2105 10/100Mbps with five twist ... -G21B4 10/100/1000Mbps with four twist-pair ports and backup optic port, managed typeF6-G20B4 10/100/1000Mbps with four ...