This is the second pair of these that I have bought. The old ones did not wear out, I just lost one in boggy ground! This after literally hundreds of miles walked, they do not pull off too easily.
They fit my Fizan walking poles, and are very hard wearing compared to those supplied with the poles.
They grip well on rock, and sink in much less than the pointy tips when on softer ground. Also, the clicking noise of the metal tips annoys me, so I use these all the time.