What are the specifications of the springboard

The springboard is 1.21 to 1.22 meters long and 20 centimeters wide, made of wood or other suitable material, painted white, and should be buried in the ground, with the surface flush with the surface of the runway and landing zone. The distance from the springboard to the remote end of the landing zone is at least 10 meters, and the distance to the proximal end of the landing zone is 1 to 3 meters.