Replacement Jar Hanger for J30 Fish Egg Hatching Jar Aquatic Invertebrate Sampling High resolution low speed impeller provides excellent R 3110 01 High resolution low speed impeller provides excellent sensitivity for measuring slow currents and low towing speeds Feature Specification Product Type Spherical Densiometer Mirror Type Concave mirrored surface Grid Pattern 24 engraved squares (96 intersection points) Housing Durable metal case Leveling Device Integrated bubble level Sighting Aids Crosshair and alignment marks Dimensions Approximately 3 × 3 in Product Code: JH The hatching jar hanger is designed to eliminate the need for a separate stand