Acrylic CURIOSITY & INTERACTIVE:Satisfying dogs curiosity. Let you receive a big welcome-home smile from your long-awaited dog through the window after your tiring day.Give you a big smile when you back to home. HEALTHY & SAFETY:ease dogs anxiety and mania, reduce barking & Digging,stress and anxiety ,Prevents Fence Jumping CONVENIENCE & FIRM:Installation time is 15 minutes, using only a drill/driver, crescent wrench and pencil. The sphere and decorative rings are made of acrylic, which is environmentally healthy and odorless.Doesn't turn yellow with prolonged use. GREAT FOR MANY USES: pet window in yard, kid window in playground/daycare centers, cover to protect a surveillance camera etc. NATIVE CUSTOMER SERVICE:instructions (Includes email and demo).expert guidance who located in USA not in other country.