Most leash products have one size cap. Oakley found that their eyewear was limited on using one size. Oakley’s Design team created two sized cap doors (small / large).Each cap door will expand / contract based on the stem size. This will allow any Rx / Sun / Sport model to use the leash. Also, the TPE rubber is similar to Oakley’s unobtainium technology. This material will stick to the stem without disrupting form, fit, and function. Angle cap shape forces the leash cord to stick straight off of the neck. Oakley designed this cap to have a slight angle. This has allowed the leash cord to rest naturally on the shoulders. Using an 18” cord is the perfect length for this product. Giving the cord more length has allowed for better comfort and performance.