This is a unique item, a second class relic (meaning it is a piece of clothing from the saint).
His coat of arms is on the right-hand side in wax.
It appears that the notation on the reverse side refers to the relic as a piece of clothing belonging to Blessed Pius X. He was beatified on June 3, 1951 (and canonized on May 29th, 1954). The notation was signed on February 17, 1953 by Maria Pia Sartor.