Gastec Sulfide Ion Detector Tubes from Nextteq accurately and rapidly measure sulfide ion levels in solution. The simple, direct-reading tubes provide results in two to three minutes. The calibration scale, printed on each tube, provides on-the-spot measurements that are easy to read. They require no color comparison chart or laboratory equipment, and the color-stain ends with a clearly defined line of demarcation to eliminate confusion and increase accuracy. They are available in four ranges for specific measurements, with a total range of 0.5 to 1,000 ppm. 877/312-2333; www.nextteq.com.