Proper support of the feet and legs is critical to the comfort of a wheelchair.
A footrest is comprised of a footrest hanger and a footplate for the user's foot to rest on while a legrest will have an pad mounted to the hanger at calf height for additional support for the lower leg as well as the footplate.
Footrests for wheelchairs are quite common. Swing away footrests can be moved to make transferring from the chair easier. The footrest hangers are set at a 90 degree angle which is the ideal position. For adults with longer legs, hangers can often be set to a 60 or 70 degree angle so as not to disrupt caster movement while keeping the seat height reasonable.
Legrests aren't as common on most wheelchairs but are typically standard on tilt wheelchairs as those users benefit from the additional support. Proper alignment of the calf pad and footplate together is vital to ensure additional pressure on the buttocks doesn't occur.