The top of the hoop is 10 feet (305 cm) above the ground. Regulation backboards are 6 feet (183 cm) wide by 3.5 feet (107 cm) tall. All basketball rims (hoops) are 18 inches (46 cm) in diameter.
Is NBA double rim or single?
Usually only outside courts use double rim. I have never seen an inside court, such as gyms and schools, use a double rim. A double rim is harder to shoot and make a shot with, especially with a bouncy ball such as a high PSI plastic ball. Most bad shots will not go in.