Energy Efficient Replacement Windows for your Denver area home! Purchasing replacement windows is a significant investment. At Pinnacle, we offer a huge selection of vinyl windows, wood windows and fiberglass composite windows from some of America’s top manufacturers. We believe in educating and informing our customers about the different window options available. There are many frame type and window operation choices, colors and glass types for a homeowner to choose from, and we are here to guide you through the process.