The inner part of the core features a cubic geometric shape that resembles the cube on the official logo of the Croatian Association for Technical Culture, conveying the message of stability, strength and geometric perfection. The cube symbolizes one of the fields of the coat of arms of the Republic of Croatia, while the twelve identical edges of the cube represent the same number of the fundamental principles of the Croatian Association for Technical Culture. The anniversary years '1946' and '2021' are inscribed in the centre of the core of the coin and the cube, while the remaining part of the core of the coin features the components of a circuit board as an important part of many electronic devices.

The inscription '75th ANNIVERSARY OF THE FOUNDATION OF THE CROATIAN ASSOCIATION OF TECHNICAL CULTURE' is arranged in a circular shape within the ring. On the upper edge of the ring there are clips placed in a circular way, which individually represent different activities of the technical culture and that are linked together forming a chain, symbol of strength and unity in the development of technical culture.

The stylized number of the denomination '25' appears in the centre of the core. The outlines of the number "25" reveal the image of a marten looking to the right, with the body of the marten embedded in the denomination number. Above the denomination appears the coat of arms of the Republic of Croatia. The name of the currency unit "KUNA" is inscribed below the number in the center of the coin. The inscription "REPUBLIKA HRVATSKA" is arranged in a semicircular manner on the core of the coin, on the surface of the ring.

A blossoming laurel branch is located to the left, below the core, on the surface of the coin ring. To the right, on the surface of the ring, a common oak branch with acorns appears. On the upper edge of the ring there are clamps placed in a circular way, which together form a chain, with the same symbolic message as in the description of the motif on the obverse.

The coat of arms of the Republic of Croatia consists of one main shield and five smaller shields which form a crown over the main shield. The main coat of arms is a checkerboard (chequy) that consists of 13 red and 12 silver (white) fields. It's also informally known in Croatian as šahovnica ("chessboard", from šah, "chess"). The five smaller shields represent five different historical regions within Croatia.