This is a great battery Hydrometer sold by Midnite Soalr. Midnite PN: MNHydrometer
The HYDROVOLT battery tester is a heavy-duty, chemical-resistant hydrometer which is direct reading and accurate at all electrolyte temperatures. Its advanced design incorporates important practical features which simplify battery service as never before.
Hydrovolt Hydrometer Features Include:
For additional information on this Hydrovolt hydrometer, see the PDF Linked below.