Watch Your Step
The XR-87 Proximity Mine is a Military Spec device which is probably the most explosive proximty device in SRPA's arsenal. It works by detecting seismic activity and then combining that with a tremor-sensitive mercury switch.
The Proximity Mine is perfect for dispatching large hordes of enemies, especially melee types like Grims and Leapers, but it's also great for setting traps. If you know where enemies are going to appear or run, you can catch them by surprise and deplete their numbers rapidly. However, it isn't very effective against boss types or Titans, as their seismic activity is too large for the sensor to read.
This weapon can only be used in the Cooperative mode of play and it is exclusive to the Spec Ops class. Ammunition is also quite difficult to come by, as it can only be obtained via the Spec Ops' special ability.