The best ones are made of air. Very light, inexpensive and you can use your hands for other things. You never see athletes using poles and if there were an advantage they would be. There is a reason humans stopped using their arms for propulsion, millions of years ago. If you have knee pain try shorter distance, slower speed or less weight (get rid of pole weight). When you break your leg you don't use crutches forever. Granted pole scream "I AM A HIKER" and they sure look cool.