MBC relay, with electromagnet and striker

Used to make experiments in Electromagnetism, different models of relays e. g.;
magnetic block "compact" (MBC) with electromagnet and trembler,
sturdy plastic housing (ABS) with transparent base, printed circuit symbol (screen-printed),
jacks also suitable for 4 mm safety plugs, base with embedded neodymium magnets
dimensions: approx. 84 x 84 x 39 mm