This product is a Weksler 4-1/2" K-Monel Bourdon 10 PSI Gauge with a back mount and a maximum pressure of 600 psi. It is made in the United States and has a face diameter of 4.5 inches (114.3 mm). The model number is DA24-3PPP-RBBO and the National Stock Number is 6685-01-327-7381.