Inside mount for widths of 23.5-23.8 inches. Requires a 2-inch minimum frame depth for inside mount. This roller window blind offers a convenient installation process without the need for any tools or drilling. Simply insert the product into the window frame, and the installation can be completed in just 1 minute. % Achieve total darkness with our window shade minimal gap design for complete light and UV ray blockage. The thermal layer ensures optimal room temperature, energy efficiency, and noise reduction.