By varying the proportions of its components such a mixture can be used to make a liquid with any refractive index over a particular range, and a variety of other properties, such as dispersion, viscosity, density, etc. For example Fused Silica Matching liquids are very useful to those working with fused silica optical fibres, windows and other optical components in coupling and refractive near field scanning applications. Optical gels with refractive indices 1.46 and 1.52 can be used for lens and fibre coupling and mode stripping. Laser liquids with refractive indices between 1.293 and 1.630 can be used with lasers as well as other optical applications due to their stability, inertness, transparency and low toxicity.