FieldCast 4Core MM Heavy Duty Cable (200m on Drum) 4Core MM Heavy Duty, 200m on drum *** MM= Multimode 50/125 OM3 Fiber Core (Blue Rings on Connector) Heavy Duty cable is a very strong and robust cable with a diameter of 6.5 mm. Use it in the field, or wherever you need the most reliable fiber optic cable connectivity at any distance. Specs our cores of protected fiber multimode 50/125 OM3 outer cable diameter 7.5 mm. color coded (four blue rings for 4Core multimode) cable length 200 meters in total robust male cable connector on both sides wound on Schill GT380 drum