The PDFM 5.1 portable Doppler flowmeter from Greyline Instruments has an ultrasonic sensor mounted on the outside of a plastic or metal pipe that shows flow rate instantly. Users enter pipe diameter with the five-button keypad; the unit then displays, totalizes and data logs in the choice of gallons, liters or any engineering units. It includes 4-20mA output and 300,000-point data logger with USB output and Windows software. A rechargeable NiMH battery powers the unit, and push-button sleep mode extends battery life. 888/473-9546; www.greyline.com.