Make: clamping, SK5, hardened
Number of grooves: 1
Please take note, that you need two valve keys per valve. For a 4-cylinder engine with 8 valves you need eg 16 keys and for a 6-cylinder engine 16V you need 48 keys.
Why you must renew the valve keys?
Because the valve keys wear out, it is advisable to renew them with the next revision from your engine or when when you install Schrick valve spring retainers and valves to quarantee a perfect form and force fit.