YOUTHINK small pet door - Noise reduction: The flap includes a brush strip to reduce noise when pets pass through the door or off the door threshold. The quiet action helps prevent startling pets or disturbing people. - Glass friendly and discreet: The YOUTHINK small pet door is transparent, so when installed on clear glass windows or doors it appears as a continuous panel. Ideal for mounting on glass windows and sliding glass doors. - Durable construction: Made of high quality ABS that is weather resistant and sturdy. The polycarbonate panel delivers a nearly unbreakable door for pets. - 4 way locking: This cat flap uses two button style locks to provide four modes: open, locked, only in (allow entry but not exit), and only out (allow exit but not entry) to control pet movement. - Size and compatibility: Designed for small dogs and cats; suitable for glass windows and doors where a discreet, durable pet entry is desired. - Use scenarios: 1) Install on a glass patio door to let small pets come and go quietly without waking you. 2) Use on a glass room divider to allow pet movement between rooms while you maintain access control. 3) Fit on sliding glass doors in apartments to provide pet access without compromising security or aesthetics.