B.M.X. Productsused this decal to identify which tubes on the frame were chromoly steel. Historically the standard frames were main frame chromoly, which consisted of the front triangle. The team bikes, in earlier Chatsworth built models, were designated by a capital letter T in front of the serial number as being full chromoly tubing.
Later models, the difference was determined by the brake bridge being solid for main frame and slotted on some all tubes, although this did not follow through on all models.