During excavations of the site of Dura-Europos in the early 1930s, two Roman horse trappers were found along with shields, arrowheads and thigh guards giving us good examples of mid-3rd century military equipment. One of these trappers, belonging to the Yale University Art Gallery, was recently conserved by the author. As a result of this work, a detailed examination of the armor was possible. This paper discusses the materials of which the trapper is made, the techniques involved in its manufacture and the method of assembly. It also incorporates the results of technical analysis undertaken in 1935 at the time the trapper was prepared for exhibition in the United States. The trapper is made from overlapping iron scales sewn down to a linen fabric backing, with the edges and center strip set off with (red?) leather. The scales were made from low-carbon bloom iron and are sewn down with rawhide.