The basic wooden ramps are low-cost, fixed height wedge-shaped ramps that are suitable for doorway kerbs between 2 inches to 5 inches high.
Bi-Fold Aluminum ramps cater for obstacles that are higher, such as two or three steps high. These are good for some houses which have such small staircases leading up to the door. They are also suitable for loading and unloading of goods.
Telescopic ramps are retractable, and are therefore suitable for bringing along in a car.