Description: Mi.No. 51/54 (PS 34/37) horizontal pair type I and II, printed on the leaf from notebook. It is known only a couple of pairs of this rare trial. Described in Vilfan on page 86 where is pictured back side of block of four. According the picture of the back, is clear that this pair is continuation of that block of four. Trace of vertical bending. Very rare (B&P auction XLIV/106). Signed Bar.