Product Package: The package contains 4 sets of nylon gate rollers, wheel size: 1.18 x 1.57 in/30 x 40mm(W * H), total length: 73mm/2.87 inch, screw size: M12*1.75.Quality Nylon Rollers: The gate roller guide rail is made of bearings + nylon. The product is sturdy and durable, with a stable structure and long service life. Nylon-wrapped wheels effectively reduce noise, and reduce friction and noise, making your sliding door run smoother and quieter.Function: The sliding door guide roller can be installed on the bracket or on the rear column wall to achieve smooth operation of the sliding door and prevent the door from tipping over from the track.Easy to Install: The sliding door guide wheel is easy to install and use. You can adjust the bracket to make the roller direction upward or downward.