rex systems inc, rex systems incorporated, rsi, defense contractor, dod contractor, cage 59475, duns 06-688-5764, duns 6-688-5764, veteran owned small business, d.o.d contracting, d.o.d contractor, apx72, apx-72, an/apx-72, an/apx72, an/usm-128, an-usm128, usm-128,usm128, enhanced marker set, smart marker, first responder, mrcs, mobile responder, soldier sensor, unattended ground sensor, sps-49, sps49, radar, iff, identify friend or foe, identified friend or foe, analog testing, digital testing, sustainment, military electronics, hazard marking, mine field marking, mine field marker, clear lane marking, clear lane marker, apx100, apx-100, an/apx-100, an/apx100