These sleeves have been torture tested by some big names in the PE world and are the favorite of "BD" and "PervMcSwerve from reddits r/gettingbigger. If you're looking for a sleeve that has the right combo of flexibility and durability for repeated folding rolling and hours of strain, then these are the ones. • Highly durable to resist tearing yet stretchy enough for easy folding/rolling. • Reinforced thicker upper portion to ensure your seal never breaks no matter what cup you use. MEASURING: • Measure the width of your FLACCID STRETCHED shaft below the glans. • ALWAYS make sure the sleeve is smaller than your current measurement as you will thin out once stretched. • When in doubt, size down for maximum seal.  Tips for care: Clean after each use. Store sleeves in a cool, dry place. Coat in baby powder to keep them from accumulating moisture after each use. Make sure your fingernails are not ragged to prevent them from tearing the sleeves. Do not leave the sleeves attached to the cups.