4-Decade Inductance Box Compact and robust, suitable for filter design, general purpose substitution and d.c. to d.c. converter design. Inductance is set by 4 easily read dials which are divided into decade values from 1mH to 10H. High permeability, custom wound ferrite cores ensure insignificant influence from external magnetic fields and maximum stability. Housed in fully screened metal case. Connection via 4mm terminals and includes a case connection.