You want the essentials? The Starter Kit gives you what you need to harness the power of you Game Boy Advance, like a Light & Screen Magnifier to bring the action brighter and closer, a Multi-Link Cable to challenge your enemies in head-to-head play, and a Car Adapter for continual play.
Light and Screen Magnifier - Brighter, more vivid graphics, enlarged screen for better viewing.
Multi-Link Cable - permits head-to-head play in Game-Link games, allows data transfer.
Power your GBA from a car power plug or cigarette lighter.