An early incarnation of the Optimus '0' with small bore all-through pump tube assembly. I don't know whether documentation exists as to when the Optimus model '0'was first introduced, but this example can't be much earlier than c. 1912. There is no 'patent' reference in the tank top legends such as an earlier dated example would have had. The pump rod assembly is the post-1908 type, and, compared to this earlier date example of the equivalent Optimus No.1, this '0' features the later relief-molded air release screw, not the earlier incuse marked version. On the other hand these 'later' components still sit in combination with an earlier type filler cap when compared to this just a little later example of a No.1.