High quality vintage steel knife or blade.
Not sure what it is used for but used in lathe or some kind of cutting machine.
Very sharp cutting edge.
Printed on it:  Registered "Zyto" mark.
and:  S. Tyzack & Son Ltd, Old Street, London. E.C.1
The blade is 23 cm long, 2.9 cm deep, and about 3 mm thick.
Few corrosion dots on surface, easily removed.