Besides what the other person stated, I've found that the ones with the ball last longer. The band ones break pretty easily and consistently after long time use. Just as a heads up, the metolius ones are expensive. Buy this instead: https://www.amazon.com/gp/product/B00BRCG3LK/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1