Virtual make tensiometer is a simple, versatile, and inexpensive instrument which provides a direct measurement of soil water tension. The modular design allows easy replacement of the ceramic cup and dial gauge, and addition of extension tubes and the Service Cap. The tensiometer is available in a variety of lengths, ranging from 6 inches (15 cm) to 90 inches (2 m). Service kit required with Soil Tensiometers (Sold extra). These instruments function with the greatest accuracy when all air has been removed. One Service Unit will service multiple instruments