Keysight technologies u1250 series handheld digital multimeters keysight technologies u1251b opt abd the u1251b is the base model of the keysight technologies u1250 series and along with the standard measurement functions of a digital multimeter provides the option of recording the values obtained almost every measurement can be read quickly and reliably because of the 50 000 digit lc display with analogue bar display and adjustable background lighting keysight technologies u1251b digital