Rod is made of durable aluminum and the length can be fixed. You first loosen the tube a bit, then pull out and then tighten again.
Ball remains securely locked by the handy locking mechanism (see video below).
Made of aluminum so light, only the 3 meter rod weighs half of that of 6 meters. You could take this into account when you carry the bag, 4 meters is a nice intermediate size eg ..
Available in three lengths: