These 3/8" vacuum tube grip caps provide a secure electrical connection to top-mounted grid terminals on power and RF vacuum tubes. Stamped from spring-tensioned brass or nickel-plated steel, the connector slides directly over 3/8" glass top caps to maintain stable contact under high voltage and elevated thermal conditions. Historically manufactured by component suppliers such as Millen, National, and Johnson, these clips are routinely used in vintage transmitters, RF power amplifiers, and vintage receiver circuits to connect plate or grid cap leads while preventing strain on the glass-to-metal tube seal.