The CO 7500 is a value for money instrument that has been designed for use in educational establishments including sixth form colleges, secondary schools, technical schools and colleges. With a large, uncluttered, digital display and simple push button controls, the instrument is ideal for students. The unit is compact and robust enough to withstand the rigours of the teaching environment, and is available in mains only or mains /internal rechargeable NiMH battery versions. The CO 7500 is easy to use. The eight filters – 440, 470, 490, 520, 550, 580, 590 and 680nm – are encased in an integral filter wheel and the wavelength required is obtained by rotating this until the relevant, colour coded, number is visible in the indicator window. The ergonomic design makes this very convenient, and filters cannot be accidentally lost or damaged. With only five buttons (on/off, reference and test, convert between Absorbance and % Transmission readings and kinetics), the instrument is ideal for beginners. When used in kinetics mode - to study rates of reaction, for example - the CO 7500 takes readings approximately every second and these can be sent to a chart recorder (via the analogue output) if required. Alternatively, the results could be downloaded to an Excel spreadsheet for graphing and other manipulation using the appropriate accessories. The samples can be measured in either standard 10mm pathlength cuvettes a minimum of 400 µl is required or in 16mm diameter test tubes (adapters for 10/12 mm test tubes are an optional accessory with the CO 7500);. There is a drain hole at the bottom of the cell compartment so that spillages do not affect the Instrument.