These climbing knickers (knickerbockers, knee pants, ect.) were made in the late 1970s or early 1980s when you could still commonly find them in climbing shops and sporting goods stores. The were rapidly falling out of fashion with most rock climbers but were still popular for cross country skiing and with hikers in certain parts of the country.
These were designed by L.L. Bean and called “Crag Masters”. This model has numerous features included with the climber or hiker in mind such as:
Tough corduroy construction
Doubled seat and knees
A simple, clean, uncluttered design for use with hip belts or swami belts (harnesses)