To help you with PED Relays, it’s useful to look at the history and the specific standard you've been asking about (NSN 5945-99-198-4019).
PED (originally Pye Electro-Devices) was a major British manufacturer of high-quality electromechanical components.
it helps to know that the company changed names several times:
1977: Formed as Pye Electro-Devices Ltd (merging Pye TMC Components and Magnetic Devices).
1983: Formed the PED brand.
1992: Merged with Belling Lee to form BLP Components.
Current Status: Much of the legacy PED technology now sits under the BLP Components or Dialight umbrellas, though many original parts are now considered "legacy" or "New Old Stock" (NOS).
This is a Military-Grade Hybrid Relay. Here is what makes "PED Relays" in this category unique:
Hybrid Design: These combine a solid-state input (for precise triggering) with mechanical contacts (for high-current "clean" switching).
Ruggedization: They were built to meet BS9000 standards, meaning they are resistant to high vibration, extreme temperatures, and moisture—essential for the marine and aerospace applications they were often used in.
Common Specs: Many PED relays used in UK defense (the "99" country code in your NSN) operate on 12v DC and are designed for PCB mounting or socket plugging.