API (American Petroleum Institute) Hydrometers

13-1996 API Gravity Hydrometers, -1 to 101 Range, Koehler Instrument Company

13-1998 API Gravity Hydrometers, 0 to 101 Range, Koehler Instrument Company

13-2000 API Gravity Thermohydrometers - Thermometer in Stem

13-1915 Hydrometers - Petroleum, API Scale, ASTM, 330mm without Thermometer, Thermco

13-1995 Thermo-Hydrometers - Petroleum, API Scale, ASTM with Thermometer in Body, 380mm, 0.2°, Thermco