The qMix gas mixing software package from Sierra Instruments is included with every QuadraTherm 640i/780i thermal mass flowmeter on a beta trial basis. It allows the user to create custom gases or gas mixtures to compensate for gas compositional changes in the field. It can be used when the gas composition changes in the pipe or when moving the meter to another location with a different gas composition. It retains accuracy without the need for gas recalibration every time the gas changes. It allows users to create and upload unlimited gas mixtures onto one meter, and save custom gas mixtures onto your personal “My Gases Database” for later use. 800/866-0200; www.sierrainstruments.com.