026-80292-00 Discontinued See TLVC810 Valve Core Tool R134A 8 Mm And 10 Mm Late Model. Those stubborn 8 mm and 10 mm valve cores on those late model vehicles don’t stand a chance with RTI's heavy-duty 026-80292-00 Valve Core Tool. Its 5-1/4 in. length combined with its 3/4 in. knurled diameter body lets this tool get the job done. The use of a 3/8 in. wrench on the hex of either adds plenty of leverage.