A luminaire comprising: a chassis (100), the chassis (100) comprising: four walls joined to form a rectangular cavity, each wall of the four walls comprising: —a heat sink (107); —a wiring channel (111, 112); —a first receiving channel (114) on a first side of the heat sink (107); and—a second receiving channel (116) on a second side of the heat sink (107); a light emitting diode board (130) attached to a first wall of the four walls; a first extrusion (344) attached to a second wall of the four walls; a second extrusion (345) attached to a third wall of the four walls; wherein the light emitting diode board (130) comprises a first protrusion that fits into the first receiving channel and a second protrusion that fits into the second receiving channel; and wherein the light emitting diode board (130) rests on the heat sink (107) of the first wall when the first protrusion is fit into the first receiving channel and the second protrusion is fit into the second receiving channel.