It doesn't say in the product title or size chart, but this 17.5 34/35 size is an XL.  For me, I wear M or L, so it's too large, particularly the sleeves are too long and the shirt is baggy on me for my 5'9" frame.  The fabric quality is nice and soft as expected from the Calvin Klein brand.  It's a regular fit style, which sits looser than your slim variety.  It's a good basic shirt for work or could work well as a white shirt with a suit.  I just wish the sizing would include the S-XL size, as is on the collar, when choosing the sizes online.