Cartridge model from the Reference series - Reference1 uses a sophisticated five-part OTL cantilever with a weight reduced by up to 5% compared to Platinum1 and Sonata1 models. The coils are wound with ultra-high purity long crystal (UHPLC) oxygen free copper wire. These cartridges are individually calibrated. Model Reference1 uses specially designed elliptical diamond Grado, in ellipse shape, 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: 2mH, Resistance: 2 Ω, Compliance CUs: 20 cm/dyne, Stylus Replacement: not possible, Mounting: S, Weight: 6.5 g.