Electronics include equipment such as Guardian ECM and Beagle Active Probe. This list also includes 'Mech upgrades such as Artemis IV FCS and weapons like Target Acquisition Gear. Electronics are loaded just like other weapons, equipments and upgrades in the 'Mech lab. Some electronics, like ECM are restricted to specific variants of 'Mech chassis. Some electronics like TAG must be mounted onto a weapon hard point. In this example, the TAG may take a place of an energy weapon. Others like Beagle Active Probe have no such restrictions and can be placed onto any 'Mech so long as that 'Mech has the available critical space and tonnage to mount them. In any case It is usually redundant or simply not possible to have more than one of any particular unit electronic equipment, although that is not to say that you couldn't have more than one type of electronic on a 'Mech.
For example you can't mount more than one ECM on any mech, even if you have the available critical space and tonnage to do so, but you could have both an ECM and Beagle Active Probe on the same 'mech. If so desired, one could even mount a TAG, an ECM and a Beagle Active Probe provided that all the tonnage, critical space, hard point restriction and variant restriction were all met.
Electronics differ from Modules unlocked in the Pilot Tree in the sense that they are actually "on" the 'Mech and can be destroyed by Critical Hits or 'lost' due to the location that they were mounted on being destroyed.
the current list of all Electronics in MWO is as followed: