Magnetic chess sets are good for outdoor play as the pieces will not fall off easily. Contrary to what the name implies, magnetic chess sets need not be 100% made of metal and a magnetic material.
Instead, the chess pieces can be made of wood, plastic or even brass with a small piece of magnet inside each piece. The boards are usually made of wood or plastic and come with a storage compartment for the chess pieces.
Other than the choice of the material, you will also need to decide whether to buy a magnetic chess set with a foldable board. A set with a foldable board is smaller when in storage and is thus more portable and great for travelling.