Segmental retaining wall unit

A retaining wall block kit includes a block and an adjustable setback bar having a break line extending along a widthwise centerline between the front surface and the rear surface. The block has alignment knuckles protruding downwardly from a bottom surface of a front section, and has a receiver channel extending laterally across a top surface of the front section for receiving the alignment knuckles of an adjacent upper block. The setback bar can be removably located within the receiver channel, and is configured to be split along the break line. Thus, the setback bar is adjustable by being modified or omitted altogether to change the distance between the alignment knuckles and a front surface of the receiver channel and thereby allow the setback of the retaining wall to be changed as desired.