VOB 4230, 4240, 4250 Spec Sheet / VOBs / By Eckel Noise Control Technologies Performance OCTAVE BAND FREQUENCY (HZ) ROOM MODEL 125 250 500 1K 2K 4K NIC NOISE REDUCTION (dB) VOB Series 19 28 38 46 52 54 40 Optional Features Door Window (Laminated) 9” x 45” (229mm x 1143mm) Castors or Isolators