The first stage letdown takes place at the trim level, which is a single or double cage, standard or low noise design. All trim combinations of 1-6933 valve are available, including the pilot operated plug for class V shutoff, except that the cage is hung and the seat welded to the body to take care of thermal gradients. For very severe service, where further noise attenuation is required, the low noise cages are substitued with a Limiphon trim (see 1-9400 series).