A buttressed anvil assembly is provided for use with a surgical stapling instrument. At least one of the antenna at the central access point and the antenna of each of the slave nodes is circularly polarized. In particular, a method for coexistence of multi-radio devices is described. The stretch band has a ribbed portion which allows the stretch band to be doubled back and secured to the cap material. The fireplace also includes a combustion air plenum system coupled to the combustion chamber enclosure to supply fresh air from the outside to the combustion chamber and an exhaust opening defined by the combustion chamber enclosure for exhausting exhaust air from the combustion chamber to the outside of the structure. The novel compounds have progestational and antimineralocorticoid activity.