The Housing for Ultimate Dual Cartridge Action An ultra-durable aluminum body ensures longevity and reliability Dual Cartridge Technology: independent adjustments for lens and aperture Aperture Locking Technology: secure and easy tool-less aperture changes Patented light baffling technology reduces glare and provides a crystal-clear image Specifications: Construction: Aluminum Color: Black DC InSight cartridges, apertures, lenses, and installation tool sold separately