Type 1419 Decade Capacitors are offered in three models using two different dielectric materials to satisfy a variety of needs.

Type 1419-A and –B (Polystyrene)
Capacitance and dissipation factor constant with frequency, essentially noninductive, very low dielectric absorption. The dielectric is specially prepared of purified high-molecular-weight polystyrene, having very high resistance and freedom from interfacial polarization. Moisture sealing with Teflon* feed-through insulators assures high performance under adverse humidity conditions.

Type 1419-K (Silvered Mica)
Higher accuracy, low dissipation factor, and +35 + 10 ppm/° C temperature coefficient (10-50° C) for use in higher ambient temperatures.

Data Sheet for the GenRad 1419 (in .pdf)