The 1 1/2" Watts 007M2 double check assembly began production in 1993 and is still currently in production. The "M" stands for modification. The 1 1/2" 007 went through two modifications for a total of three different models (007, 007M1, 007M2). Repair parts do not interchange between models so be sure of your model before ordering repair parts. The 007 is an inline check design with a single access cover. The body is of bronze construction. Fully testable.