This flir breach adapter is a mini-rail adapter you need to use the flir breach thermal imaging monocular with sionyx's dual helmet bridge (see optional accessories). this bridge allows you to attach several optics, including the flir breach, to a helmet so you can use them hands-free. This adapter replaces either the left or right arm of the dual helmet bridge, depending on which eye you want to use the flir breach for. Application flir breach adapter for dual helmet bridge (dovetail) This adapter is the missing piece you need to finally be able to attach the flir breach thermal monocular to a helmet. attaching night vision cameras/thermal cameras to a helmet is something that is very popular in survival, navigation, airsoft, mil-sims and other tactical applications. it allows you to keep both hands free during use. Do you have questions about this product or exactly what you need to attach to a helmet? Then please contact us.