Thomas Keller calls the fine mesh Tamis, Chinois, Sieve as "Tools of Refinement". These items will raise your sauces, purees, and soups to a whole new level of smooth and beautiful. Basically what you do is pass semi liquids thru the mesh to remove all pulp, seeds, skins, fibers, lumps of starch, or whatever and produce a velvet, clean, beautiful product.
The fine sieve is a tool most chefs don't have and they are frankly very hard to find. I own the set above $30 for the sieve's and $6 for the scraper. You don't need all 3 sieves but they come as a set. Both of the items above are listed as baking items. They are very useful there as well for Sieving dry ingredients and counter scraping and dough turning.
Really, you will be amazed what these simple items will do for you cooking.
The two images above are a set of Sieves and a scraper from Amazon - see link.