This is a pull-on compression sleeve, so the fit is what makes it useful. The 510-4 is the larger option in the Toros Group 510 range and has a 23 cm height, but “larger” only helps if it matches your own leg measurement. Use a flexible tape measure around the knee, in the area the sleeve will cover, while your leg is relaxed and slightly bent. Write the measurement down in centimetres and compare it with the manufacturer’s size chart printed on the packaging. Do not rely on shoe size, body weight or height alone.
A sleeve that is too small can bunch up, feel overly tight, restrict natural movement, or leave deep marks. A sleeve that is too loose can slide and will not give the gentle, even compression this product is designed for. If you are between sizes, a sensible general rule is to choose the larger size if you plan to wear the sleeve for longer periods or over a knee that tends to swell, and the smaller size if you want the firmest version of a mild hold.
Fit is also a safety point: compression should never be painful. Stop wearing the sleeve if you notice numbness, increased swelling, or signs that circulation is impaired. If the knee has been injured, operated on, or is swollen, painful or unstable, ask a medical professional before using this product at all.