ST 35 High Efficiency Compression Driver The ST 35 car audio compression driver, like the ST 25 and the ST 35, employs a CCAR (Copper Clad Aluminium Ribbon) voice coil featuring an extra-light aluminium membrane with high thermal dissipation as well as an anodized aluminium body, for maximum damping and vibration rejection. It additionally features a 44 mm (1.7 in.) voice coil and a powerful ferrite magnet, creating maximum SPL in extreme installations. Data table Size mm (in.) 35 (1.4) Power Handling - Peak W 100 Impedance Ω 4 Frequency response Hz 2,5k ÷ 20k Sensitivity dB SPL 109 Voice coil Ø mm (in.) 35 (1.4) Magnet Neodymium Cone/Dome Aluminium