An anvil assembly includes a circular anvil head that supports a crush ring,ananvil cap that supports an o-ring, and a circular anvil buttress member. Thecapconnects to the head and is movable relative to the head between approximatedandunapproximated positions. The crush ring is spaced from the cap when the capis in theapproximated position and movable into engagement with the cap to move the captothe unapproximated position. The buttress member includes a body portion andanextension portion. The body portion is supported on the head and the extensionportionis secureable between the o-ring and the head when the cap is in theapproximatedposition. The extension portion is releasable from between the o-ring and theheadwhen the cap is disposed in the unapproximated position so that the bodyportionseparates from the head.
