API hydrometers for petroleum testing measure 165mm (6.5”) in length, have 0.2° divisions and offer an accuracy of one scale division. Temperature of standardization is 60°F. 1234K74 covers the range of 69 to 81 API. 1234K75’s range is 79 to 91 API. 1234K76 covers a range of 45 to 90 API. 1234K77 is for the API range of 10 to 45.