FURUTECH F35(R) RHODIUM Male 1/8" 3.5mm to Female 1/4" 6.3mm Adapter Plug Headphone Jack Convert 6.3mm standard plug to 3.5mm stereo mini plug. audio headphone conversion plug using the material that was carefully selected. Specifications  conductor: RoHS Directive compliance rhodium plated - phosphorus bronze and copper alloy insulation: POM resin Housing: non-magnetic stainless steel external dimensions: total length 10.6mmx61.0mm