Brass body. Brass shackle. Keyway: Flat. “YALE & TOWNE MFG. CO.” is embossed on the obverse of the shackle. “STAMFORD, CONN. U.S.A.” is embossed on the reverse of the shackle. “PATENTED JAN.7.90” is stamped on the reverse of the shackle.Patent # 418884. (PK-MB-012-S2P).