An environmental test chamber artificially replicates the conditions under which machinery, materials, devices or components might be exposed. It is also used to accelerate the effects of exposure to the environment, sometimes at conditions not actually expected. As test requirements may be relatively simple or complex, environmental test chambers vary widely in size, ranging from small units designed for placement on bench tops to large walk-in chambers. Test chambers generally have viewports or video feeds to allow for visual inspection of the sample during the test. Reach-in chambers provide an opening that technicians may use to handle test samples.