I bought several sets of these for my bar, however we discovered a number of flaws. Firstly, they are not very well-made, 2 of the 4 I bought had fallen apart within 3 weeks. Also, we measured them and they are not very accurate either, we deduced they are approximately 18/36, rather than 20/40. If you are going to use them infrequently and are not that bothered about precise accuracy, then they will do you just fine. But I would not buy them if you are going to use them professionally.