We have original windows in an 110 year old house. Most of the old sash locks were broken and these look very nice as replacements as well as being sturdy. As someone else previously commented, you really need about an inch on the top sash for them to fit since the latch is 15/16" wide. They will not on fit on some of the newer windows in another part of our home. They are a little pricey but we managed to get them on sale.
Be careful, you may have 1 3/4 overall, but if the surface of your upper window where this needs to attach is the standard 5/8' of most modern windows, these won't work for you. Wish the description gave the dimensions of each half,