PRO BEAM expanded-beam optical connectors are now approved and listed in M83526/20 & 21. These rugged connectors take the delicacy out of optical interconnections. For the dust and mud of military operations and the grime and gunk of oil fields, no other style of optical connectors withstands vibration, temperature extremes, and dust and debris without performance degradation. PRO BEAM connectors clean quickly and easily in the field, without disassembly, without special tools or cleaning materials and without any danger of damaging the fiber.