ZAMST Knee Support, Knee Support, Size L, for Left Knee Outer Side / Right Knee Inner Side, RK-1Plus, Black Purchased new, tried on only, and stored without use. For support of the outer side of the left knee and the inner side of the right knee. This is a used item, so please understand before purchasing. Running Knee Support RK Series Filmista Knee, Thin, Lightweight, Marathon, Running, Jogging [For knee (outer side) problems during running] Restricts movements that put stress on the outer side of the knee, supporting the knee during running. [Reduces stress on the outer side of the knee, common among runners] Redesigned based on user feedback to achieve a more comfortable fit. The design is also carefully considered, balancing design and functionality that does not interfere with running style. [Unique rotational restraint mechanism to prevent knee twisting] The film placed under the knee and the spiral lace that pulls up in a spiral shape prevent movements (twisting) that put stress on the knee. [Aqua hole is used on the back of the knee to prevent stickiness from sweat] Aqua hole is used for the fabric on the back of the knee. The uneven fabric and water-repellent treatment disperse sweat, making it comfortable and less sticky during running. [By wearing it on the opposite leg, it also reduces the stress on the inner side of the knee, which is common among runners] By switching between the left and right legs according to your concerns, it reduces the stress on the outer or inner side of the knee. *Please be sure to check the left and right before use.