These are the individual threshold risers that make up a threshold ramp. You can use these wheelchair ramp accessories to add to an existing EZ Access Aluminum Threshold Ramp to make it higher. For instance, if you already have 4 inch threshold ramp, but need it to be five inches, you can purchase the 5" Extender to add to the ramp. These threshold riser pieces are not intended for use by themselves and are non-returnable. Order threshold parts for wheelchair ramps online today.