The QUANTAPANEL 602-PW Architectural Low-e Storm Window installs on the interior of an existing fixed panel window. Installation of the QUANTAPANEL 600 Series is through pre-drilled holes via screws that attach to the window jamb perpendicular to the plane of the window. The sash, which is removable to the interior, is retained in place by four locking bars. The patented QUANTAPANEL 600 Series provides for air infiltration reduction comparable to a prime window, which is necessary for optimum performance of an interior secondary sash system. For larger windows, the QUANTAPANEL 602-PW can have two sashes with a meeting rail, and arched configurations can be fabricated as well. This product is ENERGY STAR certified. The QUANTAPANEL 602-PW Architectural Low-e Storm Window are available in standard or custom colors (185 colors to choose from)!