Rubber Threshold Ramp Anti-Slip Textured Surface Rubber Curb Ramp for Wheelchair and Scooter Black, Wheelchair Ramp Doorway Rated (3.5" Rise). Prevent rollover and tripping ----- 3 SIDED RAMP DESIGN, in addition to the large slope on the front, there are also cushioned small slopes on both sides, greatly reducing the possibility of impact or tripping.