Gibraltar's 8mm Flanged Base Cymbal Sleeves are precisely engineered to hold your cymbal felts, and therefore your cymbals, securely in place. This minimizes extraneous rattles and noises and prevents keyholing, which can devalue and even ruin a cymbal. Gibraltar's 8mm Flanged Base Cymbal Sleeves are the safeguard many drummers rely on to protect their cymbals and their sound.