Schützinger Bench & Research and Development Spring-loaded plug 615187 - Schutzinger DI FK 02 L Ni / SW, The Schützinger DI FK 02 L Ni / SW is a black spring-loaded plug designed for use in laboratory and electrical applications. As a safety jack connector, it features a 4 mm jack socket suitable for secure and reliable connections. This single piece is ideal for precise and safe electrical testing environments. Schützinger DI FK 02 L Ni/SW Spring-Loaded Plug Black Solder Connection