Single Ring Static: This is the basic single ring rim. It is static and does not give. Double Ring Static: This rim is the strongest available and is the choice of many schools, parks, and other institutional customers. This rim will not give and carries an unconditional lifetime warranty. Heavy Duty Reflex: This is the rim most commonly chosen by our residential customers. This is a break-away style rim and is more than sufficient for most residential play. Ultra Reflex: This rim is a break-away style rim. It will bend at 30 lbs. and is recommended for customers who want the rim to give when children dunk. It carries a 5-year warranty. Collegiate Break-Away: This is a competition break-away rim. It will bend at 150-180 lbs. on a spring. This rim carries a 5-year warranty. Note: All of these are made for dunking. They are mounted to a steel plate, not to the backboard itself.