Camshaft locking tool. Machined from solid steel, chemical blackened for corrosion resistance & supplied complete with Tommy-bar. Absolutely essential tool to have if any work on the valvegear to be undertaken, the main picture shows a head that has been cracked and repaired (right!). Just because the tool was 'too expensive'. A wrecked cylinder head costs? . . . . . . . .  Make life easier for yourself and don't risk the unfortunate after effects of some garage lash-up that goes wrong.