The interior of a cage is a crucial factor in car safety. A properly designed cage will increase the strength and durability of the vehicle. A few factors should be taken into account when making the choice of the materials for a race cage. First of all, make sure the materials are of the right strength. You want to make sure you choose one that will withstand repeated impact from the opposite side of the car. A cage that provides side impact protection will also reduce the chances of the inside of the cage being damaged.