Clinical Medical Marketing supplies hospital cleaning products, sanitizing products, hand sanitizers and syringes to the health care market in Australia and New Zealand. Refractometers from Clinical Medical Marketing adhere to the most stringent manufacturing standards set by Australian authorities. Refractometers are usually used in research, clinical procedures and laboratories. A refractometer is used to measure the refractive index of materials and operates on the principle of the critical angle. Both the digital and traditional refractometers follow this principle. Traditional handheld refractometers are analogue device that measures a liquid’s refractive index. Refractometers use the critical angle principle by which lenses and prisms project a shadow line onto a small glass receptacle inside refractometers. The shadow line is observed through a magnifying glass. In practicality, a sample between a measuring prism and a small cover plate captures light travelling through the sample and passes through to the receptacle. A shadow line between the illuminated area and the dark area is formed and where the shadow line crosses the scale a reading is taken. Since refractive index is temperature dependent, only refractometers with in-built temperature compensation should be used. Nowadays, digital handheld refractometers are widely available and are much easier to use with backlight LCD displays.