Drops into a sash window: Fits in the lower half of a double-hung sash window with no cutting or drilling Aluminum or vinyl frame: Aluminum is sturdier, vinyl matches common white vinyl window frames Three flap sizes: Small, medium, and large for cats and small to mid-size dogs Widths 21.5" to 44": Stock width variants in 1.5" bands, plus a custom-width option Made in USA, locking cover included: Built domestically and backed by a 3-year warranty The Liberty Pet Door for White Sash Windows is a removable panel for double-hung sash windows with a white frame. The lower sash slides up, the panel drops in, and the sash comes back down onto it. Renter-friendly, since nothing is cut or drilled.Frame comes in aluminum or vinyl, both in white. Three flap sizes (small, medium, large). Stock widths span 21.5" to 44" in 1.5" bands, with custom-width available for non-standard sashes. A locking cover is included. Safety glass covers the area above the flap so the closed window still reads as a window.Before ordering, measure the inside width of your window sash, left to right. Pick a width range that brackets your measurement. If your window has a black frame, use the black sash version. For cat-only households, the cat-sized sash panel is smaller and more affordable.Made in the USA and backed by a 3-year warranty. Easy DIY install.