2.5mm mono plug to 6.3mm mono jack FEV-B109By gerry / February 21, 2021 2.5mm mono plug to 6.3mm mono jack FEV-B109A. 2.5mm mono plug to 6.3mm mono jack;B. 2.5mm mono plug to 6.3mm stereo jackA. 2.5mm mono plug to 6.3mm mono jack; B. 2.5mm mono plug to 6.3mm stereo jack