Quantum Companies Share: Quantum Companies Visit Website 4912 Del Ray Avenue Bethesda, MD 20814 (301) 657-9900 ext. 129 kap@quantumco.net Rep Info Map Whom to Contact Marc Kapastin 4912 Del Ray Avenue Bethesda, MD 20814 What's Nearby? Distance: 5 10 15 20 25 50 mi.