These are old stock Military Surplus Boarding Ladders. These ladders are about 43 inches from end to end. They include hand rails (see the pictures) and a rope fastening system for securing the ladder.
These ladders can be used on many different trailers both military and civilian. The ladder is pictured on my M101 3/4 Ton Trailer in the listing. Also works great on the M37 and other 3/4 Ton Trucks.
They can also be used in the back of most pickup trucks, vintage or modern.