The QUANTAPANEL 607-SL Architectural Low-e Storm Window installs on the interior of an existing horizontal slider 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. A compressible seal on the perimeter of the frame ensures a tight seal, and allows for slight out-of-square conditions in the window opening. This 2-track system has a "stationary" removable sash in the outer track, and an inner sash that opens horizontally to allow for fresh air ventilation. 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. This product is ENERGY STAR certified. The QUANTAPANEL 607-SL Architectural Low-e Storm Window are available in standard or custom colors (185 colors to choose from)!