VDO Vision represents a true technological advancement in instrument illumination and installation. Using fiber optic technology, VDO pointers offer unmatched readability. VDO's Trioptic through-dial lighting provides superb night illumination. For maximum flexibility and ease of installation without metal brackets, nuts, or washers, the VDO Spin-Lok Mounting System uses a spin-on clamp to hold the instrument with 360° of force, preventing panel warping or gauge rotation. Mechanical pressure and temperature gauges have metal housings with U-clamp brackets. 2-1/16" diameter except speedometer and tachometer.