These lightweight ramps come in two widths: 32" and 36" (36" width is compatible with ADA standards). They work for rises up to 4". These ramps have holes punched in the top corners and the hardware needed to easily secure the ramp to the surface. Many people prefer this style of ramp because it is difficult to steal. If you don't have a storm door , you can place the ramp right onto the door threshold plate and screw it down with supplied hardware. If you do have a storm door , we suggest first securing a strip of treated wood to the outside of the door threshold...at the proper height so that the storm door won't run into the threshold ramp. Next, you can secure the ramp to the piece of treated wood. Mfg's Model No. TH