TLDR: Sizing is wrong - order based on how wide/slim/medium your legs are. Your height is irrelevant. Otherwise good product. I'm a medium BMI, slim build male and the XS/S was the best size for me.

Here's the detail - the picture with sizing information implies to order a size based on your height in cm. DO NOT do this. Your height has nothing to do with the different sizes available. The 3 sizes (XS/S - M/L - XL/2XL) all have the same vertical drop of 71cm. The only thing that changes is the circumference (or leg width). If you measure the inside of the elasticated band that holds it up above your knee, you get these approximate measurements:

XS/S - 32cm circumference
M/L - 34cm circumference
XL/2XL - 38cm circumference

The best size for me was XS/S even though my leg measurements are:

35cm at 8cm above middle of knee cap when standing (and 37cm when sitting with leg at 90 degrees) - this is where I have the top of the leg warmer.
34cm immediately above my knee when standing (and 35cm when sitting with leg at 90 degrees)
34cm around my central knee when standing (and 35cm when sitting with leg at 90 degrees)

Only the XS/S would stay up when walking more than 2 steps - it fits quite well in fact. The only part of the leg warmers that is elasticated is the top band (it stretches several cm) along with the black leather-looking triangle material that you can see on the top half of the leg warmer. Unfortunately the top buckle strap is mostly useless because it is not elasticated. Unless you have a knee many cm larger than the area above it, then the buckle won't help much or at all. The bottom buckle can hold the warmer up effectively (for me) because my calf is much wider then the area just below the knee. But you will want the top part to stay up too (otherwise you would get a crumpled pile falling below the knee, unlike the pictures).

Be aware that unless you wear massive platforms then this will probably scrape along the ground - but I think that is part of the style.

They do help keep your legs warm (they have a ?medium thickness) but I would suggest their primary function is style and not thermal insulation.

Finally, the picture is true to the product. In case you overlook the details like I did - they each have 4 wide bands of alternating light and dark red. Only one leg has a black pressed rubber strip in the shape of several crosses and the other does not.