The SteelPhase SP01 is a modern low noise audio enhancer, with built in LiPo battery for over 20 hrs use. Unique features include a Mode switch to accept stereo and mono wiring, and a 3 position Filter. Designed and tested by prospectors for prospectors, with very good results on the Minelab SDC2300*, GPZ7000 and GPX series. It works extremely well with headphones and external speakers alike.