Schützinger Bench & Research and Development Spring-loaded plug 615189 - Schutzinger DI FK 15 S Ni / BL, The Schützinger spring-loaded plug, model DI FK 15 S Ni / BL, features a 4 mm pin diameter and comes in blue. It is a safety jack plug designed for laboratory use, ensuring secure and reliable electrical connections. This plug is typically used in testing and measurement equipment where safe and robust connections are required. Schützinger DI FK 15 S Ni/BL Spring-Loaded Plug 4mm Pin Blue 1pc