Be confident in your purchase we're an Authorized Milwaukee Dealer. How cool is that?!?!? Features: The Milwaukee Double Junction ORP Platinum Electrode is probe specifically designed for the continuous analysis of aquariums. Top features include: DOUBLE JUNCTION: The double junction design reduces risk of clogging leading to more stable ORP measurement and reduced maintenance. GEL FILLED: Using a gel removes the need to maintain the electrolyte levels. PLATINUM ELECTRODE: The platinum electrode is long lasting with little maintenance required. RESIN BODY: The resin body is highly durable, chemically resistant and protects against accidental breakage of the sensing bulb. Specs: Body: PEI Resin Reference: Double, Ag/AgCl Junction: Ceramic Electrolyte: Gel ORP Range: 2000 mV Tip Shape: platinum pin Dimensions: 6.4 inches Recommended Operating Temperature: -5 to 70C (23 to 158F) Cable length: 6.6 feet The MA921B/2M probe is designed for use with Milwaukee Monitors and Controllers.