Bluelab pH PenHighly Accurate and Dependable pH Pen Pinpoint your pH & temperature with a single tool a 2 in 1 Bluelab pH Pen. Bluelab is one of the industry's best known and most trusted brands; all of their testing equipment delivers a level of reliability and accuracy that's second to none. The Bluelab pH Pen is a handheld pH pen that's easy to use, producing clear, accurate readings on an easy to read, backlit LCD screen. By gathering the most accurate readings