One Size, Medium, but fits like a XL (exactly like the one I wear on my YouTube Channel videos dating 2020-2021.  I have it loose in case you wear clothes underneath.  Why Silk?  Because it keeps you warm, but breathes when it is hot.  It doesn't have as much static as the other fabrics.  It also feels so good on your skin.  It is handmade in Florida by Betty.  Limited Supply.  I have been in a search for the right fabric that allows less sticking of hair into it, and this is it by far.  I do not wear a shirt underneath. So, when your clothing is trash because of the amount of prickled hair in it because of this hairy job, you will find your smock will be in better shape.  Try one today!  I have used the same smock for almost a year and have not had to replace.  I choose the hand wash cycle on the washing machine and I hang dry.