What's wrong with a custom size? I replaced two small windows with triple glass ones, and just ordered the right size online. I don't think it's even possible t

What's wrong with a custom size? I replaced two small windows with triple glass ones, and just ordered the right size online. I don't think it's even possible to buy windows in a standard size (whichever that may be) here in the Netherlands. A professional glazier would order the windows from the factory just as the shop with a fancy website with a configurator did for my order.