3 3/8" X 5 3/8" (86mm X 137mm)

(front skirt) SO3 / STAS 810-52              

(rear skirt) T and S intertwined in a square

Picture courtesy Don Mecklenborg

3 3/8" X 5 3/8" (86mm X 137mm)

(front skirt) S.O.3. / STAS 810-52              

(rear skirt) T and S intertwined in a square

Picture courtesy Bob Berry

3 3/8" X 5 3/8" (86mm X 137mm)

(front skirt) SO3 - 1STAS810-73              

Picture courtesy Bob Berry