A radio removal tool is a specially designed device used to help remove a vehicles radio from the dash without causing damage to either the radio or the surround.

Different car manufacturers require different radio removal tools (pictured here is the tool for Ford).

The reason many manufacturers secure the radio using these specialized devices is part of the security system to prevent theft. So although it can be annoying to have to buy a special tool to remove something as simple as a radio, it is there for a purpose.