Keithley 2110系列：5½ 位双显示器 USB 万用表，订购信息如下：
2110-100: 5½-digit USB Digital Multimeter (100V)
2110-120: 5½-digit USB Digital Multimeter (120V)
2110-220: 5½-digit USB Digital Multimeter (220V)
2110-240: 5½-digit USB Digital Multimeter (240V)
2110-100-GPIB: 5½-digit USB and GPIB Digital Multimeter (100V)
2110-120-GPIB: 5½-digit USB and GPIB Digital Multimeter (120V)
2110-220-GPIB: 5½-digit USB and GPIB Digital Multimeter (220V)
2110-240-GPIB: 5½-digit USB and GPIB Digital Multimeter (240V)
