the three most wheelchairs unloader used by disable seniors in the United States

I need 2 pages essay talking about the three most wheelchairs unloader used by disable seniors in the United States. a introduction will be required.for the body ,a full description of each wheelchair unloader will be necessary (the cost of each wheelchair,the number of disable seniors using each type of wheelchair unloader, how the wheelchair unloader works,the weight of each wheelchair ,the maximun weight that each wheelchair unloader can take,,the good and bad sides of each wheelchair unloader,if possible talk about the material used for each wheelchair unloader)