Hydrogen Test Pen Specifications: - Model: smy8qotc1n - Dimensions: 183 x 37mm / 7.2 x 1.5in - Weight: 139g / 4.9oz - Material: ABS - Waterproof: IP67 - H2 Range: 0-2400ppb (0-2.400ppm) - Resolution: 2ppb (0.002ppm) - Accuracy: ��10ppb (0.01ppm) - Temperature Range: 0.1-60.0��C (32.0-140��F) - Battery: 3x1.5V LR44 (not included) - LCD with backlight for clear reading - Auto temperature compensation (0-60��C) - Auto shutdown after 5 minutes Features: - Detachable probe for easy use - High sensitivity for accurate measurements - Durable ABS construction Usage: 1. Remove protective cover 2. Power on and immerse probe (do not exceed marked line) 3. Stir gently and wait for stable reading 4. Clean with distilled water after use Applications: Swimming pools, hydroponics, aquariums, labs, water purification, gardening Package includes: 1 x Hydrogen Test Pen (no battery) 1 x User manual Note: Clean electrode after each use. Normal calibration variance of ��20ppb at 224ppb.