A canister for use with a luminaire, the canister having an interior heat sink incorporated into and within a top cover of the canister and a source of illumination retained within the canister. The heat sink includes a multiplicity of air fins separated by air gaps, the air fins extending radially from an interior wall of the cover. The heat sink also includes a multiplicity of air fins separated by air gaps, the air fins extending radially from an interior wall of the canister. The top cover has an opening and a removable sealing cap having a recessed surface extends into an interior of the top cover when affixed to the top cover to enclose the opening.