As a luminaire type with broad utility, bulkhead/oyster fixtures must be flexible to suit a wide variety of environments and applications. This new Tio luminaire provides that versatility through robust protection from ingress and impact, material selection which is durable in many indoor and outdoor environments, adjustable-power electronics, and a simple aesthetic which blends in to any space. Long-life components and improved luminous efficacy lend the Tio to situations where energy efficiency is a priority, and this can be further enhanced by integrating an optional occupancy/daylight sensor for stand-alone automated control.