What Are Agricultural Shingles?

The plan shingles have three main flaps(lack of better word). The agricultural shigles have smaller pieces overlapping the three main flaps. This gives the look of an older cedar roof. They come in different thickness so they last different amounts of time. They are applied  like the other shingles. You place four nails above the tar line on the front of the shingle , spaced out evenly. They should be placed stagger. Start the frist row with a whole shingle. The second row with half shingle. Then repeat up roof. If any over hang off other side cut with saw.