Most earbuds had protruding plastic tabs left over from the manufacturing process that were taped over. I had to cut and remove portions of the ribbon and then remove the plastic tabs to allow the inserts to fit snugly into the slots. Poor quality control during the manufacturing process would result in the inserts not fitting flush. You do not need to fix any defects for the product to work properly. After removing the tabs, the inserts fitted snugly, but still didn't fully mate with the grille. Acceptable for the price.