Click to expand Tap to zoom HM Digital Replacement pH Sensor for PH-200 by One Stop Hydro Save $-49.95 $49.95 | / SKU HMDSPP2 1 2 3 4 5 6 7 8 9 10+ Quantity Quantity Add to cart This item is a recurring or deferred purchase. By continuing, I agree to the cancellation policy and authorize you to charge my payment method at the prices, frequency and dates listed on this page until my order is fulfilled or I cancel, if permitted. This spare pH sensor is for HM Digital Waterproof pH Meter model P-200. Features glass pH sensor and reference tube and thermister.