Cartridge model from the Reference series - Sonata1 uses a sophisticated four-part OTL cantilever with a weight reduced by up to 10% compared to the Prestige series. The coils are wound with ultra-high purity long crystal (UHPLC) oxygen free copper wire. Model Sonata1 uses specially designed elliptical diamond, mounted in Nude. The Reference Series by Grado uses wooden structure from a handmade processed mahogany with a fixed coil. That ensures a optimal acoustic qualities. Needle module made of one piece for better tracking and eliminating vibrations. Reference models available in 1/2" mount. Specifications: Frequency Response: 10 - 60 000 Hz, Principal: MI, Channel Separation at 1KHz: 40, Input Load: 47 kΩ, Output at 1KHz 5CM/sec.: 5mV, Recommended Tracking Force: 1.5 g, Stylus Type: E, Inductance: 45mH, Resistance: 475 Ω, Compliance CUs: 20 cm/dyne, Stylus Replacement: not possible, Mounting: S, Weight: 6.5 g.