The product is a Swagelok SS-4-VCR-P stainless steel VCR face seal fitting, specifically a 1/4" plug.  Shipping is free. This fitting is designed for use in hydraulics, pneumatics, pumps, and plumbing systems, and is commonly used in industrial applications. Swagelok is a well-known brand in the industry for their high-quality fittings and adapters.