U-92A/U to U-174/U Headphone Extension Cable The headphone extension line is used for helicopter. It is original civilian cables, stretchable coiling type or straight line type U-92A/U to U-174/U. 【Civilian Headphone Extension Cable】Coiled U-92A/U to U-174/U Helicopter Civilian Headset Extension Cable, U-92A/U is the corresponding parent of U-174/U.