The male connector of the ISO 6149 connection has an O-ring and a straight thread. The female half has a machined surface, a chamfer, and a straight thread. The O-ring on the male sits on the chamfer of the female port. The ISO 6149 connection is similar to the SAE J1926-1O-ring Boss except that the former has metric threads. The O-ring on the male connector is compressed into the chamfer to create a seal. The straight threads engage to form a mechanically strong connection.