The Tenebraex Anti-Reflection Device (ARD) was developed to camouflage reflections from riflescopes and binoculars optics, it also works as a sun guard the benefit of blocking sun glare or reflections from getting inside the scope. The 4x32 Tenebraex killFlash ARD was design to attach directly to the (M38x1) threaded objective housing. Works with the 4x32 BCO, 4x32 BTO, & 4x32 BSO.