This month's pump of the month will be the Bowser 310, 318, 410, and 418.

The Bowser 310 clock face Xacto Sentry pump was produced between 1929-1934. The Bowser 318 Varley Sentry is basically the same pump as the 310 but with a Varley meter, and was produced from 1930-1934.

The Bowser 410 Xacto Sentry pump was produced between 1933-1937. The Bowser 418 Varley Sentry was again the same pump as the 410 but with a Varley meter, and was produced between 1933-1936.