The Conbraco 4S-600/4SG-600 is a double check detector assembly ( DCDA ). The 2 1/2″ – 8″ sizes were produced from 1998 -2014. The 10″ size is still being produced. The 4SG-600 has been in production since 2008 and utilizes a grooved end body. The body is made of ductile iron with a fused epoxy coating. The 4S-600/4SG-600 utilizes a ½” 4S-103 as its bypass assembly.