VNA Calibration Kits from Multiple Manufacturers
VNA Calibration Kits are used to calibrate Vector Network Analyzers right before they are used for testing. They provide a reference point for the VNA before it is used to make measurements. These are usually manufactured by the company that develops the test equipment, however, they can also be purchased from a third party. Third party solutions are usually much cheaper and work with most VNA brands. As brand specific cal kits might work with their line of test equipment.
everything RF has listed VNA Cal kits from the leading manufacturers. You can select the kit based on the interface i.e connector type or waveguide size. Download the datasheet to learn more about the Cal Kits.