The ZX Interface 2 measures 116mm wide x 71mm long x 30mm high. It is supplied with two covers that pop out to reveal the joystick connectors. The ROM cartridge slot cover is hinged and opens up to the vertical.
The rear of the ZX Interface 2 provides a through connector that is only designed to be used by the ZX Printer. As such it is narrower in width than the normal Spectrum edge connector.
The inside of the casing is shown below.