Both options are available in Thermal Heart TM and standard aluminium.
The Window Factory can supply joinery for your builder to install or we offer full manufacture and installation service. The benefit of a one stop joinery shop is warranty. When the installation is done by The Window Factory we will warranty not only the joinery but also the installation and water tightness of that installation. There can be no arguments over whether warranty falls under installation or manufacture.
The best way to decide on which product to use is to have one of our specialist sales reps to do a site visit. We will be able to inspect the current joinery, learn your requirements and then recommend a product.