The BK Precision Model 5491B-220V 50,000 Count Dual Display Bench Multimeter with RS232 Interface, 220 V is a versatile and dependable bench multimeter suitable for applications in education, service and repair, and manufacturing requiring basic and reliable measurements. Additionally, this meter enhances your productivity with built-in math functions and USB connectivity, features not found in other bench meters in this price category. Math operations Rel, Max/Min, dBm, dB, %, and Hold provide educators with a convenient tool to teach basic math concepts.