Insight Technology VLI (Visible Light Illuminator) was the selected weapon light system in the original SOPMOD M4 accessory kit. It was issued to the USSOCOM communities in the late 1990s and early 2000s. VLI is an extremely powerful visible illuminator that emits a highly concentrated beam of visible light for acquisition and identification. It is powered either by 3 CR-123A batteries or by 6 AA batteries. It can be used with Night Vision devices and can be used as either a handheld illuminator or can be weapon mounted to accurately direct fire as well as illuminate and designate targets.