A bit of explanation regarding the Palmer rear risers:
Rear risers are the 6”-tall vertical supports that are shown extending up from the horizontal side bars, as highlighted in the red circle in the accompanying image. In most cases, these rear risers are unnecessary structurally as the rear of the counter is supported at the wall with the provided Palmer metal bracket (hidden) anyway. The elimination of these components reduces cost as well, so going “riser-less” shaves a bit off the retail price.
Risers will never (almost never…) be used with a china or porcelain sink, as typically sinks of this type will not have a flat area at the underside in the rear to receive the tops of these risers. This is the reason the no-riser designation is /C…the C in this case designating use for a China (porcelain) counter.
Another consideration for going “riser-less” is that a larger towel can be hung on the horizontal return bar without the interruption of the riser…not so important in a smaller powder room, but perhaps important in a space with a shower and a need to hang wider bath towels.
Rear risers would not be compatible with the new Palmer Auxiliary Towel Rail option, as the riser and rail would present a bit of a “cluttered” arrangement of parts.
Why go with risers?
Despite some of the reasons shared above regarding foregoing the rear risers, these parts are quite often specified as their inclusion does satisfy a visual (and functional) preference in many cases. The risers provide some visual heft to the rear of the console, balancing the feel of the front vertical legs. For extra-heavy counters, risers will absolutely provide additional support, transferring load to the wall flanges and the front legs.