Triple groove collets for small bore. 1.043" (26.5mm)diameter x 3.44"(26.5mm) exhaust valve for all small bore castings. These valves are produced in EN214N steel and require manganese/silicon bronze alloy valve guides. They are stellite tipped and are only available in the later triple collet groove as fitted on all post 1980 heads and heat treated to eradicate wear from unleaded petrol.