MIDI cable for computer sound cards lets you connect your musical instrument that has a MIDI In/Out connectors to your sound card.

The sound card usually has the connector type that lets you connect joystick to the computer. In order to use MIDI capabilities of the card you'll need a cable which is usually sold separately of the sound card. The cable has on its one end the Joystick type connector that should be inserted into the sound card and also an extension cord with the same kind of connector that the sound card, so that you could connect both your instrument and joystick at the same time.

On it's other end the cable has two MIDI connectors, each is a big round 5-pin connector. One connector is for MIDI Out and the other for MIDI In of your keyboard.