Aquarium Systems (A Marineland Company) Instant Ocean Hydrometer is an improved design of its preceding model #TK502. It delivers precise full-range salinity and specific gravity readings - accurate to 0.001 every time. An improved easy-fill convenience keeps hands dry. It has a durable, permanent needle mount & easy-to-read 2-color scale with "safe zone" with an extra-wide stabilizer base. Ideal for use in water temperatures of 68 to 85 degrees F. Accurate to plus or minus 0.001. Shipping-Weight: 0.7 lb |