This trail is made up of a combination of doubletrack and singletrack. The part from Bocca di Trat (1.581m) to Malga Pranzo (1.039m) is a doubletrack. At the beginning, it is steep and rough with a lot of loose gravel and small rocks. Later on, the trail surface gets better and the steepest sections are paved by concrete.
From Malga Pranzo, you'll come to a junction that heads to Capanna Grassi. Make sure you follow the dirt road to Campi only for 150m. Take the old trail on the right hand (marked path #402) to Campi (688m). Here, the trail turns from the wide doubletrack to a rocky singletrack. The rocks are bigger in the beginning. As you ride, either the trail becomes smoother or you'll get better at maneuvering through the rocks.
You'll reach the small town of Campi at the upper end. If you're going to Riva, turn right at the asphalt road before entering the old town and crossing the creek. If instead you want to head to Tenno, you have to turn left at the main road.