Seven2Go S4-Basic; Dissolved oxygen portable meter.High quality data on-the-go.Seven2Go’s simplified menu, automatic sensor recognition, and calibration reminder ensure users obtain high quality data quickly and easily.Comfortable One-Handed Operation.Seven2Go's easy-to-reach hardkey buttons and sleek design ensure comfortable one-handed operation. even in wet conditions and prolonged use.Rugged investment that lasts.Seven2Go's IP67 design, reduced weight, and rugged uGo carrying case ensure a lasting instrument providing reliable data even under harsh conditions.