1928A $1 Silver Certificate, Scarce Experimental Issue, X06577908B, Very Fine, but with light superficial wallet stain at the back-right quadrant.

For the first time since the introduction of small-size currency during the depression, the BEP produced a quantity of notes to test different paper composition to experiment with the ratio of linen and cotton. A control group using the standard paper bore the Z-B serial number block while groups with experimental paper were designated X-B and Y-B. This example is an X-B experimental note that falls within the serial number range of 10,728,000 printed. These notes remain very elusive to collectors as not many were saved at the time of issue.