SUNNEN VS-1005 RAPID VALVE SEAT CHECKER. QUICKLY AND ACCURATELY CHECKS OUT ROUNDNESS AND RUNOUT OF THE CRITICAL INTERSECTION BETWEEN TOPPING AND SEAT ANGLES. ,001" READING INDICATOR STAYS RIGHT SIDE UP FOR EASY READING AS GAGE CHECKS FULL 360 DEGREES OF THE SEAT. WORKS OFF THE SAME PILOT USED FOR GRINDING THE SEAT.