100% Polyester IMPORTANT: Measuring accurately is critical to get the correct size for your classroom window. Before you order, please read the instructions about how to measure and review our "How To" picture. STANDARD AND CUSTOM SIZING: IMPORTANT: Please add 3" to your glass width and 3" to your length before choosing your size to ensure a proper fit. Available in 9 standard sizes which cover most interior windows in elementary, middle and high schools, as well as universities and colleges. We also offer custom sized shades to fit any window, such as sidelights, media centers, and entrance ways. QUICK-RELEASE VELCRO STRAP: Every second counts during a lockdown. The most effective shade must be easily and quickly secured at the top AND bottom of the window. EASY TO INSTALL, EASY TO USE: Unlike many window blinds and blackout curtains, no tools, hardware, mounting brackets, or drilling is required. Strong adhesive tabs hold the shade in place. Simply release the Velcro strap at the top so the shade drops over the window and press bottom of shade in place to completely block the intruder’s view. DON’T WAIT UNTIL IT’S TOO LATE: When an active shooter can see into your classroom, students and teachers become targets. A blackout shade can save lives, but it is crucial that it completely blacks out the classroom to effectively ensure the safety and security of everyone. Our shades are much safer options than blackout paper shades or blackout blinds for windows. Excellent on keeping out full sun light and prevent 100% UV ray, it completely blacks out the classroom to effectively ensure the safety and security of everyone. Great option for Classroom and front doors, patio door, front porch, pergola, cabana, covered patio and living room/Bedroom.The insulated classroom door window cover can be easily attached with Velcro to tie up. Easy installation without any tool, no curtain rod necessary.Come in a wide range of solid color, sizes to suit every kind of home and every type of decor preference.