The jackets with long sleeves are ideal for Taiji Quan (Tai Chi Chuan) but also some kungfu styles use them. The latter often or in combination with a sash (purchased separately). They are available in different colors of satin or fine cotton, some with embroidery.
About clothing sizes: the size is indicated in the body length in centimeters. So a pants or jacket size 170 means that it is suitable for someone with a body height of 170 cm. If you are of average build and you choose a suit that suits your height, it will fit loosely; in other words, the suits are spacious.