Model No. SRB-4STANDARD MEGOHM BOX :Used as reference standard to be used with Million Meg-Ohm MeterModel MM-107 or MM-108D or Digital Insulation TesterModel SRB-4 ( 8 different Values)Ranges 2M, 20M, 200M, 2G, 20G, 50G, 100G & 200 Gohm resistances.Max. Applied Voltage = 1000V upto 20Mohm , 5000V for 200Mohm &above values , Accuracy of Resistances : ± 5% .Special Feature : Provision for dehumidifier is provided in the acrylic box &you can have stable readings even in rainy season.