A MagJack (formerly Bel Mag) from BEL / Bel-Stewart Connector Integrated Connector Module (ICM for short) is a combination of up to 10 discrete components. They include: The RJ45 connector, impedance matching transformers or magnetics for 10 baseT, 10/100 baseT, 1000 baseT gigabit ethernet (PoE, PoE+ for VoIP are optional,) 2 LED's, 4 termination resistors, 1 high voltage capacitor, and often common modes chokes as well.

Today's ethernet or LAN hardware engineers have two ways to lay these components out on their boards. First, they can do it "discretely." That is, they can lay out each of the parts mentioned individually on the board, and this is the way it was typically done up until the late 1990's. The second, and I believe the better way, to attack this problem, is to use a MagJack, (formerly "Bel Mag") or ICM - Integrated Connector Module, from BEL.

Gigabit Ethernet 1 Port	0826-1X1T-23-F1 , 0826-1X1T-23-F , 0826-1X1T-43-F, 0826-1X1T-43-F1
	Single port RJ45 connector, 1000 base T gigabit ethernet transformer / magnetics, 1:1 turns ratio, tab up, 12 core, for use with physical layer transceivers (PHY) like: Marvell Alaska: 88E1111, Ultra 88E1011, Ultra+88E1011S, 88E1010, 88E1010S, 88E1000, 88E1000S Broadcom: BCM5411, BCM5421, BCM5421S, BCM5461, BCM5461S National Semiconductor: DP83861 Vitesse: VSC82111, VSC8221
Gigabit Ethernet 2 Port	0826-1X2T-23-F , 0826-1X2T-43-F
	Dual port RJ45 connector, 1000 base T gigabit ethernet transformer / magnetics, 1:1 turns ratio, tab up, 12 core, for use with physical layer transceivers (PHY) like: Marvell Alaska II: 88E1020, 88E1020S, 88E1040S, 88E1041S, 88E1042S Broadcom: BCM5402, BCM5404, BCM5424, BCM5434, BCM5482
Gigabit Ethernet 4 Port	0826-1X4T-23-F1 , 0826-1X4T-23-F, 0826-1X4T-43-F
	Quad port RJ45 connector, 1000 base T gigabit ethernet transformer / magnetics, 1:1 turns ratio, tab up, 12 core, for use with physical layer transceivers (PHY) like: Marvell Alaska Quad:  88E1145, 88E1042H, 88E1041, 88E1041S, 88E1040, 88E1040S  Broadcom: BCM5464, BCM5464R, BCM5464S, BCM5464SR, BCM5466R, BCM5466SR, BCM5488, BCM54980 Vitesse: VSC8224, VSC8234, VSC8244, VSC8538, VSC8558
10/100 Fast Ethernet 1 Port	08B0-1X1T-06-F (commercial temp) 08B0-1X1T-36-F (extended temp) (08B0-1X1T-06-F1, & 08B0-1X1T-36-F1 & SI-46001-F, SI-16001-F)
	Single port RJ45 connector, 10/100 base T gigabit ethernet transformer / magnetics, 1:1 turns ratio, tab up, 4 core, for use with physical layer transceivers (PHY) like: AMD: Am79C874 Broadcom: AC101, AC101L, BCM5202, BCM5220, BCM5221, BCM5222, BCM5241 ICS: ICS1890 ICS1891 ICS1892 ICS1893 Intel: S82555 S82558 S82559 LXT970, LXT971, LXT972, LXT973 Marvell: 88E3061, 88E3081, 88E3082, 88E3083 Microchip: ENC28J60 National Semiconductor: DP83840A, DP83843, DP83223, DP83846A, DP83847 DsPHYTER II, DP83848C, DP83848I, DP83848YB
10/100 Fast Ethernet 4 Port	08B0-1X4T-36-F, 08B0-1X4T-06-F, 08B0-1X4T-36-F1, 08B0-1X4T-06-F1 (0810-1X4T-36-F, 0810-1X4T-06-F)
	Quad port RJ45 connector, 10/100 base T gigabit ethernet transformer / magnetics, 1:1 turns ratio, tab up, 4 core, for use with physical layer transceivers (PHY) like: AMD: Am79C871, Am79C872, Am79C873 Broadcom: BCM5208R, BCM5226, BCM5228, BCM5238, BCM5248, BCM5203, BCM5204 , BCM5205, BCM5208, BCM5209, BCM5216, , BCM5218, BCM5304, BCM5308 Intel: LXT9785 Marvell: 88E3060, 88E3061, 88E3080, 88E308, 88E6050
10 BaseT	08B0-1X1T-27-F
	Single port RJ45 connector, 10 base T ethernet transformer / magnetics, 1:1 turns ratio, tab up, 3 core, for use with physical layer transceivers (PHY) like Cirrus Logic CS8900A
1000 BaseT Gigabit with PoE/VoIP	0826-1X1T-80-F , 0826-1X1T-80-F1
	Single port RJ45 connector, 10/100 base T ethernet transformer / magnetics and PoE/VoIP capability, 1:1 turns ratio, tab up, 8 core
10/100 BaseT with PoE/VoIP	0826-1X1T-57-F, 0826-1X1T-57-F1
	Single port RJ45 connector, 10/100 base T ethernet transformer / magnetics and PoE/VoIP capability, 1:1 turns ratio, tab up, 6 core
10/100 BaseT with PoE "plus" / VoIP	0838-1X1T-W6 BUY NOW!
	Single port RJ45 connector, 10/100 base T ethernet transformer / magnetics and PoE "plus" / VoIP capability
1000 BaseT Gigabit with PoE "plus" / VoIP	0838-1X1T-W7
	Single port RJ45 connector, 1000 baseT gigabit ethernet transformer / magnetics and PoE "plus" / VoIP capability