The K-7511 ultralow-range dissolved oxygen test kit from CHEMetrics can be used as the primary method for determining DO levels down to 2 ppb, a means to verify (and calibrate) readings obtained by online methods, or as a backup method if an online system is not operational. It eliminates the need for calibration or routine maintenance requirements associated with online methods. It is not subject to salinity or dissolved gas interferences. Low-range DO test kits include a special sampling tube for use with boiler feedwater. This device allows the user to break the tip of the vacuum-sealed ampoule in a flowing sample stream in order to preclude error from contamination by atmospheric oxygen. The kit contains everything needed to perform 30 tests. 800-356-3072; www.chemetrics.com