Caution: As influx turbulences vary between different fans models and setups (e.g. different fan speeds, grill shapes, mesh patterns, overall flow resistance, etc.), it is not possible to reliably predict how much of an improvement adding inlet spacers will make. While the improvements are significant in most configurations, there sometimes may be little to no improvements and, in rare situations such as with particular slit-type grills, adding spacers may even lead to undesirable results with particular fan models.
Please see our performance guidelines for further information. If in doubt, detach the fan from your application, then hold it in place with no distance first and 5mm distance next. This will give you a rough indication of how much improvement you can expect in your individual configuration.
