The text in the scan form a 1924 Hubbard and Company product catalog is hard to read. It says: "Pierce Transposition Brackets Multipoint Brackets Pierce Multipoint Transposition Brackets are made with an angle steel back to which presteel points are rivited. These brackets are equiped with spiral spring steel threads for insulators having a standard one-inch pin hole. The No. 237 bracket is for two-wire transposition. The No. 437 is used for transposing the four wires to two toll circuits on which a phantom circuit is connected. Both brackets are furnished with 3/8-inch "U" bolts for 3 1/4 x 4 1/4-inch cross-arms, unless otherwise specified. "U" bolts for any size of arms up to 4 x 5 inches can be furnished at the same price".
Joslyn Manufacturing also made the same style bracket but used their own patented pressed metal threads.
I have one of these finished in light blue porcelain and another in raw metal. The raw metal piece has a flat metal angle brace attached at the top lower point angling up to the cross-arm thus keeping the bracket vertical to the cross-arm.