Hi, thanks for your good question. :) Our product is made of **muslin fabric**, not linen. Muslin is a type of fabric that is cotton and breathable; it has a softer and lighter texture compared to linen. Regarding size: For 1.78 cm height and 80 kilos, **size M** will generally be suitable. However, muslin fabric has a comfortable and loose fit; if you want a more fitted look, size M can be preferred, and if you want a looser and casual style, size L can also be preferred. I suggest you check the size chart in the product description. If you have any other question I am happy to help. :) Best regards, Deniz Madmext Team