Portamate PM-3014 Extension Couplers for Extending PM-3500 Mobile Base up to 78", Black Easily extend the footprint of your PM-3500 Mobile Base by attaching an additional rail; PM-3036, to the included 20" or 25" rail Add coupler to attach a 25" to a 36" rail for a max size of 78" Add coupler to attach a 20" to a 36" rail for a max size of 73" Easy assembly, hardware included Accommodates extra-large tools